Add native RND and ASC functions

Implement bounded random integers with lazy clock seeding and add ASC as the inverse of CHR. Cover dispatch, validation, deterministic LCG output, UTF-8 round trips, function reference, and the breakout tutorial.

Closes #16.

Co-authored-by: andrew <andrew@aklabs.net>

docs/12-function-reference.md

@@ -9,6 +9,7 @@ so a call with the wrong number is a syntax error rather than a surprise.
 | Function | Args | Form | What it gives |
 |---|---|---|---|
 | `ABS` | 1 | `ABS(n)` | The absolute value of an integer or float. |
+| `ASC` | 1 | `ASC(A$)` | The Unicode code point of a string's first character. |
 | `ATN` | 1 | `ATN(n)` | Arctangent, in radians. |
 | `BUMP` | 1 | `BUMP(1)` | Which sprites have collided, as a bitmask. **Reading clears it.** |
 | `CHR` | 1 | `CHR(n)` | The character for a Unicode code point, as a string. |
@@ -29,6 +30,7 @@ so a call with the wrong number is a syntax error rather than a surprise.
 | `RGR` | 1 | `RGR(f)` | The `GRAPHIC` mode (0), the drawing surface's width (1) or height (2) in pixels, or a character cell's width (3) or height (4). |
 | `RIGHT` | 2 | `RIGHT(A$, n)` | The rightmost `n` characters. Clamped. |
 | `RMENU` | 2 | `RMENU(n, f)` | A menu's state: field 0 the highlighted entry, field 1 whether it has been confirmed. **Reading field 1 clears it.** |
+| `RND` | 1 | `RND(n)` | A random integer from 0 up to but not including `n`. |
 | `RWINDOW` | 1 | `RWINDOW(f)` | The current text window's rows (0) or columns (1). Field 2 is a C128 screen mode and is refused. |
 | `RSPCOLOR` | 1 | `RSPCOLOR(n)` | One of `SPRCOLOR`'s two shared registers, 1 or 2. |
 | `RSPHIT` | 2 | `RSPHIT(n, f)` | One of `SPRHIT`'s settings for sprite `n`, in `SPRHIT`'s own argument order: 0 the kind, 1 to 4 the two corners. |

docs/17-tutorial-breakout.md

@@ -685,9 +685,9 @@ seconds asks for fifty frames a second.
 ### Why `GOTO` rather than `DO ... LOOP`
 
 A `DO ... LOOP` around the frame would read better, and it is not usable here: **a `GOTO`
-that jumps out of a `FOR` or a `DO` does not release the loop's scope.** There are 12
+that jumps out of a `FOR` or a `DO` does not release the loop's scope.** There are 32
 scopes, so a game that leaves its main loop once per lost life stops on the
-twelfth one:
+thirty-second one:
 
 ```basic
 N# = 0
@@ -700,7 +700,7 @@ PRINT "SURVIVED " + N#
 ```
 
 ```output
-? 3 : PARSE ERROR Environment pool exhausted at line 3 (12 in use)
+? 3 : PARSE ERROR Environment pool exhausted at line 3 (32 in use)
 
 ```
 
@@ -1005,20 +1005,48 @@ IF NUDGE# = 1 THEN GOSUB UNSTICK
 LABEL UNSTICK
 NUDGE# = 0
 STALL# = 0
-RMAX# = 4
+BVX# = (RND(4) * 3) - 6
-GOSUB RANDOM
-BVX# = (RND# * 3) - 6
 IF BVX# = 0 THEN BVX# = 3
 RETURN
 ```
 
-### You have to write your own random numbers
+### Random numbers are built in
 
-**There is no `RND` in this dialect**, and no `INT`, `SQR`, `ASC` or `TIMER` either. A
+There is no `INT`, `SQR` or `TIMER` in this dialect, but
-linear congruential generator is nine tokens and does the job. Put the number of possible
+`RND(n)` returns an integer from zero through `n - 1`. It seeds itself
-answers in `RMAX#` and read the result from `RND#`:
+from the host clock the first time it is called, so a program only needs the bound:
 
 ```basic
+I# = 0
+FOR I# = 1 TO 5
+  PRINT "ROLL " + (RND(6) + 1)
+NEXT I#
+END
+```
+
+Use `RND` for the serve, too, so the ball does not always leave in the same direction:
+
+```basic norun
+LABEL SERVE
+PX# = (SCW# - PW#) / 2
+HELD# = 1
+BX# = PX# + ((PW# / 2) - 4)
+BY# = PY# - 10
+BVX# = BSPD#
+IF RND(2) = 0 THEN BVX# = 0 - BSPD#
+BVY# = 0 - BSPD#
+PDEC# = 0
+GOSUB SHOWSPR
+RETURN
+```
+
+<details>
+<summary>Historical aside: the LCG this chapter used to teach</summary>
+
+Before `RND` existed, this nine-token linear congruential generator was copied into
+every program. It remains a useful from-scratch PRNG example:
+
+```basic norun
 SEED# = 12345
 RMAX# = 6
 RND# = 0
@@ -1035,43 +1063,11 @@ RND# = MOD((SEED# / 65536), RMAX#)
 RETURN
 ```
 
-```output
+The multiplication stays inside a 64-bit integer for any seed below 2147483648. The
-ROLL 1
+answer is taken from the middle bits because the low bits of a power-of-two modulus
-ROLL 5
+barely change from one call to the next. This used to be required; it is now built in.
-ROLL 2
-ROLL 1
-ROLL 2
-```
 
-The multiplication stays inside a 64-bit integer for any seed below 2147483648, which is
+</details>
-why the modulus is that number. The answer is taken from the middle bits — `SEED# / 65536`
-— because the low bits of a power-of-two modulus barely change from one call to the next.
-Integer division truncating for free is the `INT` you do not have.
-
-Seed it from the clock at startup. `TI#` is the host's uptime in sixtieths of a second,
-which is different every time the game is run:
-
-```basic norun
-SEED# = TI#
-```
-
-Use `RANDOM` for the serve, too, so the ball does not always leave in the same direction:
-
-```basic norun
-LABEL SERVE
-PX# = (SCW# - PW#) / 2
-HELD# = 1
-BX# = PX# + ((PW# / 2) - 4)
-BY# = PY# - 10
-RMAX# = 2
-GOSUB RANDOM
-BVX# = BSPD#
-IF RND# = 0 THEN BVX# = 0 - BSPD#
-BVY# = 0 - BSPD#
-PDEC# = 0
-GOSUB SHOWSPR
-RETURN
-```
 
 `HELD#` is the flag Step 6's loop tests: while it is 1 the ball sits on the paddle, and
 `HOLDBAL` keeps it there:
@@ -1422,9 +1418,7 @@ PX# = PX# + D#
 RETURN
 
 LABEL DEMOAIM
-RMAX# = 81
+DOFF# = RND(81) - 40
-GOSUB RANDOM
-DOFF# = RND# - 40
 RETURN
 ```
 
@@ -1501,7 +1495,7 @@ This is the shape of the whole file:
 LABEL SETUP           the geometry from Step 2
                       the declaration block from Step 3
                       the brick faces from Step 5
-                      SEED# = TI#
+                      RND(n) seeds itself from the host clock
                       the ceiling from Step 9
                       GOSUB MKSPR       Step 4
                       GOSUB SNDPROBE    Step 14
@@ -1576,10 +1570,7 @@ BB# = 0
 RX# = 0
 N# = 0
 MROW# = 0
-RMAX# = 2
-RND# = 0
 SND# = 0
-SEED# = 0
 P$ = ""
 H$ = ""
 S$ = ""

docs/18-tutorial-breakout-artwork.md

@@ -1423,8 +1423,7 @@ IF STATE# = 2 THEN GOSUB UNSTICK
 RETURN
 
 LABEL PRESSPAUSE
-IF STATE# = 2 THEN STATE# = 6 : GMTYP# = 0 : BAN$ = "PAUSED"
+IF STATE# = 2 THEN STATE# = 6 : GMTYP# = 0 : BAN$ = "PAUSED" : GOSUB SETBANNER : RETURN
-IF STATE# = 6 THEN GOSUB SETBANNER : RETURN
 IF STATE# = 6 THEN STATE# = 2 : BAN$ = "" : GOSUB SETBANNER
 RETURN
 ```

examples/megademo/README.md

@@ -56,10 +56,7 @@ This is a tour of the interpreter's edges, on purpose:
   counterpoint: a genuine 24x21 `SPRSAV` type-in sprite, 63 bytes, which is
   everything `DATA` has room to say. The paint is the reveal, and the exit is a
   stride-63 column dissolve — 63 is coprime to 160, so the walk hits every
-  column once and looks random while carrying no state. The strings come in
+  column once and looks random while carrying no state.
-  64-character chunks because a source line is 80 columns, like the machines
-  this pretends to be — the decoder carries its cursor from one `IM$` entry to
-  the next, and the generator refuses to cut inside a run.
 - **And then the picture is video.** Six delta frames loop the floor grid toward
   you and crawl the sun's slice pattern — full motion video, 1.3 KB total, about
   220 bytes a frame. A delta re-encodes only the rows that changed: an `R`
@@ -85,10 +82,6 @@ This is a tour of the interpreter's edges, on purpose:
   batch a bar of noise drums. Noise is real: `ENVELOPE`'s sixth argument is a
   waveform, 0 to 3, which Chapter 7 forgot to mention. Voice 1 carries the tune so
   the collision blips (voice 2) and scene sweeps (voice 3) never steal its channel.
-  A batch is four `PLAY` statements, one bar each — the 80-column line limit will
-  not hold four bars in one string, and it does not need to: the parser's voice,
-  envelope and duration state persists across statements and every `PLAY` appends
-  to the same queue, so four bars queue exactly as one line would.
 
 It also probes for its hardware like a proper boot loader, with one `TRAP` per
 device: no graphics refuses by name and exits, no audio mutes the soundtrack, no

examples/megademo/megademo.bas

@@ -461,78 +461,38 @@ BS% = W# / 160
 IF BS% < 1 THEN BS% = 1
 REM  ---- PICTURE-BEGIN (generated by vaporwave.py; do not
 REM  ---- hand-edit -- rerun the script to change the picture)
-DIM IM$(56)
+DIM IM$(16)
 DIM VA#(6)
 DIM VB#(6)
-NS# = 32
+NS# = 9
-VA#(0) = 32
+VA#(0) = 9
-VB#(0) = 35
+VB#(0) = 9
-VA#(1) = 36
+VA#(1) = 10
-VB#(1) = 39
+VB#(1) = 10
-VA#(2) = 40
+VA#(2) = 11
-VB#(2) = 43
+VB#(2) = 12
-VA#(3) = 44
+VA#(3) = 13
-VB#(3) = 47
+VB#(3) = 13
-VA#(4) = 48
+VA#(4) = 14
-VB#(4) = 51
+VB#(4) = 14
-VA#(5) = 52
+VA#(5) = 15
-VB#(5) = 55
+VB#(5) = 15
-IM$(0) = "G9G9G9G9GPGHEHG9GTEHG9GTEHGPGPEHG9GTEHG9GTEHGHGXEHGTBAG8EHG9GTEH"
+IM$(0) = "G9G9G9G9GPGHEHG9GTEHG9GTEHGPGPEHG9GTEHG9GTEHGHGXEHGTBAG8EHG9GTEHG5EHGPEHG5EHGPEHG5EHGAPAG3EHGPEHG5EHGPEHGXGHEHG5EHGPEHG5EHGFBAGIEHGPGPEHGPEHGHEHGPEHGPEHGHEHGPEHGHEHGPEHGPEHGHEHGBPAGMEHGPEHGHEHGPEHGHEHGPEHGPEHGHEHGPEHGPEHGHEHGPEHGHEPGHEHGPEH"
-IM$(1) = "G5EHGPEHG5EHGPEHG5EHGAPAG3EHGPEHG5EHGPEHGXGHEHG5EHGPEHG5EHGFBAGI"
+IM$(1) = "GHEPGHEHGPEHGHEPGHEHGHEGBAEHGHEHGPEHGHEPGHEHGPEHGHEHGPEHGHEPGHEHGPEHGHEPGHEHGPECPAEDGHEPGHEHGHEPGHEPGHEHGHEPGHEPGHEHGHEPGHEHGHEPGHEPGHECBAEDGHEPGHEPGHEHGHEPGHEHGHEPGHEPGHEHGHEPGHEPEPGHEPGHE5GHEPGHE5GHEHEXGHEPGHEEPAEZGHEPGHE5GHE5GHEPGHE5GHEP"
-IM$(2) = "EHGPGPEHGPEHGHEHGPEHGPEHGHEHGPEHGHEHGPEHGPEHGHEHGBPAGMEHGPEHGHEH"
+IM$(2) = "GHE5GHE9ETGHE9ETGHEXEHGHE9ETGHHAE9ESGHEPEPGBBAGEE9EMHOE9ETGHEHE9E7HUE9E6E9E4H0E9E3E9E3H2E9EHBAETEHKHE9ELH6E9ECKHEPEPKHE9EBH9HAE9EIKHEHEXKHE2H9HCE9EPKHE5KHEPKDH9HEKCEPKHE5KHE5KHEKH9HGEBKHEPKHEXEHKHE5KHEBH9HIEIKHEPKHEPEPKHEPKHEHKAH9HKKHEHKHEP"
-IM$(3) = "GPEHGHEHGPEHGPEHGHEHGPEHGPEHGHEHGPEHGHEPGHEHGPEHGHEPGHEHGPEHGHEP"
+IM$(3) = "KHEHKHEPKHEPKHH9HMEGKHEHKHEPKHEHKHEPKHEPH9HMEOKHEHKHEPKHEHKPEHKHEGH9HOKFEPKHEHKPEHKHEHKPEHKGH9HOEFKHEPKHEHKHEPKHEHKPEFH9HQKEEHKHEPKHEHKHEPKHEHKMH9HSKLEHKHEPKHEHKPEHKHEHKEH9HSEDKPEHKPEHKHEHKPEHKHEEH9HSKDEHKPEHKPKPEHKPEHKDH9HUECKHEHKPEHKHKXEH"
-IM$(4) = "GHEHGHEGBAEHGHEHGPEHGHEPGHEHGPEHGHEHGPEHGHEPGHEHGPEHGHEPGHEHGPEC"
+IM$(4) = "KPEDH9HUKCEHK5EHK5EHKLH9HUKKEHK5EHK5EHKCH9HWEBKPEHKXKHEHK8I9IWKZEHKPKPEHK0I9IWK7EHKHKXEHKSI9IWK9KFEHK9KOI9IWK9KNK9KOI9IWK9KNK9KOI9IWK9KNKPIHKZI9IYK6IHKHKXIHKSI9IWK9KFIHK5IHKKI9IWK9KNIHK5IHKCI9IYKPIHKXKHIHK5IHKPIHK5IHKPIHKPKPIHK0I9IWKJIHKPIH"
-IM$(5) = "PAEDGHEPGHEHGHEPGHEPGHEHGHEPGHEPGHEHGHEPGHEHGHEPGHEPGHECBAEDGHEP"
+IM$(5) = "KHIHKPIHKPI9IZKBIHKHIHKPIHKHIHKPIHKKI9IWKJIHKHIHKPIHKHIHKPIHKDI9IXKPIHKHIHKHKHIHKHIPKHI9IYKCIHKPIHKHIHKPIHKHIPKHIHKPIHKHIPKHIHKPIHKHIHKPIHKHI9I9IHKHIHKPIHKHIPKHIHKHIEC9CSKDIPKHIPKHIHKHIPKHIHKEC9CSIDKHIPKHIPIPKHIPKHIFC9CQKEIHKHIPKHIHIXKHIPKG"
-IM$(6) = "GHEPGHEHGHEPGHEHGHEPGHEPGHEHGHEPGHEPEPGHEPGHE5GHEPGHE5GHEHEXGHEP"
+IM$(6) = "C9COIFKHI5KHI5KHIPKHI5KHIPKHI5KHI5KHIPKHI5KHIPKHIXIHKHI9IDC9CMI4KHIPIPKHI6C9CKI9IDKHIHIXKHIZC9CII9IMKHI9IWC9CGI9IVI9I9I9I9IPI9I9I9I9IPQ9Q9Q9Q9QPE9E9E9E9EPE9E9E9E9EPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9"
-IM$(7) = "GHEEPAEZGHEPGHE5GHE5GHEPGHE5GHEPGHE5GHE9ETGHE9ETGHEXEHGHE9ETGHHA"
+IM$(7) = "Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9"
-IM$(8) = "E9ESGHEPEPGBBAGEE9EMHOE9ETGHEHE9E7HUE9E6E9E4H0E9E3E9E3H2E9EHBAET"
+IM$(8) = "Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QP"
-IM$(9) = "EHKHE9ELH6E9ECKHEPEPKHE9EBH9HAE9EIKHEHEXKHE2H9HCE9EPKHE5KHEPKDH9"
+IM$(9) = "RBRQ9QOKMQHK5RBSQ9QTI9IRRBXQ9QTKPQHKHQPKERBYQ9QPI9IHRB3Q9QSKAI5KHIJRB5Q9QTC9CMRB9Q9QWI9IGRCBQ9QYC9CCRCIA9A9A9A9APRCJE9E9E9E9EPRCNA9A9A9A9APRCOE9E9E9E9EPRCUA9A9A9A9APRCVE9E9E9E9EPRC5A9A9A9A9APRC7E9E9E9E9EP"
-IM$(10) = "HEKCEPKHE5KHE5KHEKH9HGEBKHEPKHEXEHKHE5KHEBH9HIEIKHEPKHEPEPKHEPKH"
+IM$(10) = "RBQQ9QOK9KIQHKFRBRQ9QOI9IQRBWQ9QPKLQHKHQHKPRBXQ9QTI9QLIERB2Q9QRIBKHIPKHIPKCRB4Q9QSC9CORB8Q9QVI3KHIGRCAQ9QXC9CERCJA9A9A9A9APRCKE9E9E9E9EPRCOA9A9A9A9APRCPE9E9E9E9EPRCVA9A9A9A9APRCXE9E9E9E9EPRC7A9A9A9A9APRDAE9E9E9E9EP"
-IM$(11) = "EHKAH9HKKHEHKHEPKHEHKHEPKHEPKHH9HMEGKHEHKHEPKHEHKHEPKHEPH9HMEOKH"
+IM$(11) = "RBPQ9QOK9KAQHKNRBQQ9QOI9IWRBVQ9QOKEQHKHQHKPQHKFRBWQ9QPI9IPRB1Q9QQKCIPKHIPKHIDRB3Q9QSC9CORB7Q9QUIWKHIPRB9Q9QWC9CGRCEA9A9A9A9APRCFE9E9E9E9EPRCGA9A9A9A9APRCHE9E9E9E9EPRCPA9A9A9A9APRCQE9E9E9E9EPRCXA9A9A9A9APRCZE9E9E9E9EPRDAA9A9A9A9APRDCE9E9E9E9"
-IM$(12) = "EHKHEPKHEHKPEHKHEGH9HOKFEPKHEHKPEHKHEHKPEHKGH9HOEFKHEPKHEHKHEPKH"
+IM$(12) = "EP"
-IM$(13) = "EHKPEFH9HQKEEHKHEPKHEHKHEPKHEHKMH9HSKLEHKHEPKHEHKPEHKHEHKEH9HSED"
+IM$(13) = "RBOQ9QNK3QHKWRBPQ9QOI9IWRBUQ9QTKHQHKPQHKNRBVQ9QOI9IWRB0Q9QQIKKHIPKHIHKDRB1Q9QQC9CSRB2Q9QRC9CQRB6Q9QTIPKHIYRB8Q9QVC9CIRCKA9A9A9A9APRCLE9E9E9E9EPRCQA9A9A9A9APRCRE9E9E9E9EPRCZA9A9A9A9APRC1E9E9E9E9EPRDCA9A9A9A9APRDFE9E9E9E9EP"
-IM$(14) = "KPEHKPEHKHEHKPEHKHEEH9HSKDEHKPEHKPKPEHKPEHKDH9HUECKHEHKPEHKHKXEH"
+IM$(14) = "RBOQ9QNI9IYRBTQ9QOKEQHKPQHKVRBUQ9QTI9IRRBZQ9QTKHQHKPQHKHRB0Q9QQC9CSRB5Q9QTIHKHI5KARB7Q9QUC9CKRCBQ9QYI9ICRCHA9A9A9A9APRCIE9E9E9E9EPRCLA9A9A9A9APRCME9E9E9E9EPRCRA9A9A9A9APRCTE9E9E9E9EPRC1A9A9A9A9APRC3E9E9E9E9EPRDFA9A9A9A9APRDIE9E9E9E9EP"
-IM$(15) = "KPEDH9HUKCEHK5EHK5EHKLH9HUKKEHK5EHK5EHKCH9HWEBKPEHKXKHEHK8I9IWKZ"
+IM$(15) = "RBSQ9QTKPQHK3RBTQ9QOI9IWRBYQ9QPKDQHKPQHKHRBZQ9QTI9ILRB4Q9QSIAKHI5KHIBRB6Q9QTC9CMRCAQ9QXI9IERCEE9E9E9E9EPRCFA9A9A9A9APRCGE9E9E9E9EPRCMA9A9A9A9APRCNE9E9E9E9EPRCTA9A9A9A9APRCUE9E9E9E9EPRC3A9A9A9A9APRC5E9E9E9E9EPRDIA9A9A9A9AP"
-IM$(16) = "EHKPKPEHK0I9IWK7EHKHKXEHKSI9IWK9KFEHK9KOI9IWK9KNK9KOI9IWK9KNK9KO"
-IM$(17) = "I9IWK9KNKPIHKZI9IYK6IHKHKXIHKSI9IWK9KFIHK5IHKKI9IWK9KNIHK5IHKCI9"
-IM$(18) = "IYKPIHKXKHIHK5IHKPIHK5IHKPIHKPKPIHK0I9IWKJIHKPIHKHIHKPIHKPI9IZKB"
-IM$(19) = "IHKHIHKPIHKHIHKPIHKKI9IWKJIHKHIHKPIHKHIHKPIHKDI9IXKPIHKHIHKHKHIH"
-IM$(20) = "KHIPKHI9IYKCIHKPIHKHIHKPIHKHIPKHIHKPIHKHIPKHIHKPIHKHIHKPIHKHI9I9"
-IM$(21) = "IHKHIHKPIHKHIPKHIHKHIEC9CSKDIPKHIPKHIHKHIPKHIHKEC9CSIDKHIPKHIPIP"
-IM$(22) = "KHIPKHIFC9CQKEIHKHIPKHIHIXKHIPKGC9COIFKHI5KHI5KHIPKHI5KHIPKHI5KH"
-IM$(23) = "I5KHIPKHI5KHIPKHIXIHKHI9IDC9CMI4KHIPIPKHI6C9CKI9IDKHIHIXKHIZC9CI"
-IM$(24) = "I9IMKHI9IWC9CGI9IVI9I9I9I9IPI9I9I9I9IPQ9Q9Q9Q9QPE9E9E9E9EPE9E9E9"
-IM$(25) = "E9EPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QP"
-IM$(26) = "Q9Q9Q9Q9QPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9"
-IM$(27) = "Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9"
-IM$(28) = "QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9"
-IM$(29) = "Q9Q9Q9QPE9E9E9E9EPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9"
-IM$(30) = "Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QP"
-IM$(31) = "Q9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QPQ9Q9Q9Q9QP"
-IM$(32) = "RBRQ9QOKMQHK5RBSQ9QTI9IRRBXQ9QTKPQHKHQPKERBYQ9QPI9IHRB3Q9QSKAI5"
-IM$(33) = "KHIJRB5Q9QTC9CMRB9Q9QWI9IGRCBQ9QYC9CCRCIA9A9A9A9APRCJE9E9E9E9EP"
-IM$(34) = "RCNA9A9A9A9APRCOE9E9E9E9EPRCUA9A9A9A9APRCVE9E9E9E9EPRC5A9A9A9A9"
-IM$(35) = "APRC7E9E9E9E9EP"
-IM$(36) = "RBQQ9QOK9KIQHKFRBRQ9QOI9IQRBWQ9QPKLQHKHQHKPRBXQ9QTI9QLIERB2Q9QR"
-IM$(37) = "IBKHIPKHIPKCRB4Q9QSC9CORB8Q9QVI3KHIGRCAQ9QXC9CERCJA9A9A9A9APRCK"
-IM$(38) = "E9E9E9E9EPRCOA9A9A9A9APRCPE9E9E9E9EPRCVA9A9A9A9APRCXE9E9E9E9EP"
-IM$(39) = "RC7A9A9A9A9APRDAE9E9E9E9EP"
-IM$(40) = "RBPQ9QOK9KAQHKNRBQQ9QOI9IWRBVQ9QOKEQHKHQHKPQHKFRBWQ9QPI9IPRB1Q9"
-IM$(41) = "QQKCIPKHIPKHIDRB3Q9QSC9CORB7Q9QUIWKHIPRB9Q9QWC9CGRCEA9A9A9A9AP"
-IM$(42) = "RCFE9E9E9E9EPRCGA9A9A9A9APRCHE9E9E9E9EPRCPA9A9A9A9APRCQE9E9E9E9"
-IM$(43) = "EPRCXA9A9A9A9APRCZE9E9E9E9EPRDAA9A9A9A9APRDCE9E9E9E9EP"
-IM$(44) = "RBOQ9QNK3QHKWRBPQ9QOI9IWRBUQ9QTKHQHKPQHKNRBVQ9QOI9IWRB0Q9QQIKKH"
-IM$(45) = "IPKHIHKDRB1Q9QQC9CSRB2Q9QRC9CQRB6Q9QTIPKHIYRB8Q9QVC9CIRCKA9A9A9"
-IM$(46) = "A9APRCLE9E9E9E9EPRCQA9A9A9A9APRCRE9E9E9E9EPRCZA9A9A9A9APRC1E9E9"
-IM$(47) = "E9E9EPRDCA9A9A9A9APRDFE9E9E9E9EP"
-IM$(48) = "RBOQ9QNI9IYRBTQ9QOKEQHKPQHKVRBUQ9QTI9IRRBZQ9QTKHQHKPQHKHRB0Q9QQ"
-IM$(49) = "C9CSRB5Q9QTIHKHI5KARB7Q9QUC9CKRCBQ9QYI9ICRCHA9A9A9A9APRCIE9E9E9"
-IM$(50) = "E9EPRCLA9A9A9A9APRCME9E9E9E9EPRCRA9A9A9A9APRCTE9E9E9E9EPRC1A9A9"
-IM$(51) = "A9A9APRC3E9E9E9E9EPRDFA9A9A9A9APRDIE9E9E9E9EP"
-IM$(52) = "RBSQ9QTKPQHK3RBTQ9QOI9IWRBYQ9QPKDQHKPQHKHRBZQ9QTI9ILRB4Q9QSIAKH"
-IM$(53) = "I5KHIBRB6Q9QTC9CMRCAQ9QXI9IERCEE9E9E9E9EPRCFA9A9A9A9APRCGE9E9E9"
-IM$(54) = "E9EPRCMA9A9A9A9APRCNE9E9E9E9EPRCTA9A9A9A9APRCUE9E9E9E9EPRC3A9A9"
-IM$(55) = "A9A9APRC5E9E9E9E9EPRDIA9A9A9A9AP"
 REM  ---- PICTURE-END
 SS# = 0
 SE# = NS# - 1
@@ -1357,25 +1317,13 @@ TB# = TB# + 1
 IF TB# > 2 THEN TB# = 0
 RETURN
 
-REM  A batch is four PLAY statements, one bar each: the parser's V, T,
-REM  U and duration state persists across statements and every PLAY
-REM  appends to the same queue, so four bars queue exactly as one long
-REM  string would -- which the 80-column line limit no longer allows.
-REM  Each bar restates the prefix anyway, so a bar dropped by QFULL
-REM  never leaves the next one playing with drum-kit state.
 LABEL TUNEA
-PLAY "V1T3U9S O1AO2AO3AO2AO3AO4CEAO1AO2AO4CEAO5CO4AE"
+PLAY "V1T3U9S O1AO2AO3AO2AO3AO4CEAO1AO2AO4CEAO5CO4AE O1FO2FO3FO2FO3FAO4CFO1FO2FO3AO4CFAO5CO4A O1CO2CO3CO2CO3CEGO4CO1CO2CO3EGO4CEGO5C O1GO2GO3GO2GO3GBO4DGO1GO2GO3BO4DGBO5DO4B"
-PLAY "V1T3U9S O1FO2FO3FO2FO3FAO4CFO1FO2FO3AO4CFAO5CO4A"
-PLAY "V1T3U9S O1CO2CO3CO2CO3CEGO4CO1CO2CO3EGO4CEGO5C"
-PLAY "V1T3U9S O1GO2GO3GO2GO3GBO4DGO1GO2GO3BO4DGBO5DO4B"
 MT# = TI# + 270
 RETURN
 
 LABEL TUNEB
-PLAY "V1T3U9S O1AO2AO3AO2AO3AO4CEAO1AO2AO4CEAO5CEO4A"
+PLAY "V1T3U9S O1AO2AO3AO2AO3AO4CEAO1AO2AO4CEAO5CEO4A O1FO2FO3FO2FO3FAO4CFO1FO2FO3AO4CFAO5CO4A O1DO2DO3DO2DO3DFAO4DO1DO2DO3FAO4DFAO5D O1EO2EO3EO2EO3E#GBO4EO1EO2EO3#GBO4E#GBO5E"
-PLAY "V1T3U9S O1FO2FO3FO2FO3FAO4CFO1FO2FO3AO4CFAO5CO4A"
-PLAY "V1T3U9S O1DO2DO3DO2DO3DFAO4DO1DO2DO3FAO4DFAO5D"
-PLAY "V1T3U9S O1EO2EO3EO2EO3E#GBO4EO1EO2EO3#GBO4E#GBO5E"
 MT# = TI# + 270
 RETURN
 

examples/megademo/vaporwave.py

@@ -58,14 +58,7 @@ SKIP = "Q"
 ROWREC = "R"
 LENCH = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 MAXRUN = len(LENCH)
-
+PAYLOAD = 240
-# The interpreter reads source through an 80-byte line buffer and refuses
-# any line that fills it (AKBASIC_MAX_LINE_LENGTH, sink_stdio.c), so a
-# stored line is at most 78 characters plus its newline. 'IM$(NN) = "' and
-# the closing quote spend 12 of those; 64 keeps the emitted lines under
-# the ceiling with margin to spare while the index stays two digits.
-PAYLOAD = 64
-MAXLINE = 78
 
 SUN_CX, SUN_CY, SUN_R = 80, 50, 30
 HORIZON = 74
@@ -213,32 +206,13 @@ def encode_delta(prev, cur):
 
 
 def chop(blob):
-    """Split a stream into strings of at most PAYLOAD characters, cutting
+    return [blob[i:i + PAYLOAD] for i in range(0, len(blob), PAYLOAD)]
-    only between records. The decoder reads a record's tail characters
-    with MID on the string it is walking, so a run (two characters) or a
-    row record (three) that straddled two IM$ entries would decode as
-    garbage; DRAWSTREAM only carries the cursor, never a partial record."""
-    out, cur = [], ""
-    p = 0
-    while p < len(blob):
-        n = 3 if blob[p] == ROWREC else 2
-        if len(cur) + n > PAYLOAD:
-            out.append(cur)
-            cur = ""
-        cur += blob[p:p + n]
-        p += n
-    if cur:
-        out.append(cur)
-    return out
 
 
-def simulate(raster, blob, x=0, y=0):
+def simulate(raster, blob):
     """Apply one encoded stream to a raster exactly the way the BASIC
-    decoder does, skips-draw-nothing and all. The cursor comes in and
+    decoder does, skips-draw-nothing and all."""
-    goes back out because DRAWSTREAM carries it from one IM$ entry to
+    x = y = p = 0
-    the next -- decoding the chopped strings one at a time with the
-    cursor threaded through is exactly what the demo will execute."""
-    p = 0
     while p < len(blob):
         c = blob[p]
         if c == ROWREC:
@@ -256,31 +230,20 @@ def simulate(raster, blob, x=0, y=0):
             x = 0
             y += 1
         p += 2
-    return raster, x, y
-
-
-def simulate_lines(raster, lines):
-    """One stream as its chopped strings, cursor carried across the
-    boundaries the way DRAWSTREAM carries X# and Y#."""
-    x = y = 0
-    for line in lines:
-        raster, x, y = simulate(raster, line, x, y)
     return raster
 
 
-def verify(frames, base_lines, delta_line_groups):
+def verify(frames, base_blob, delta_blobs):
     """The base must reproduce frame 0 exactly, and each delta must
     carry the raster exactly to the next frame. A skip leaves the cell
     the encoder promised was already right, so equality is total and
-    any difference at all is an encoder bug. This decodes the CHOPPED
+    any difference at all is an encoder bug."""
-    strings, not the blobs, so a chop that split a record would fail
-    here instead of corrupting the screen."""
     raster = [[1] * W for _ in range(H)]
-    raster = simulate_lines(raster, base_lines)
+    raster = simulate(raster, base_blob)
     assert raster == frames[0], "base stream does not reproduce frame 0"
-    for i, lines in enumerate(delta_line_groups):
+    for i, blob in enumerate(delta_blobs):
         want = frames[(i + 1) % PHASES]
-        raster = simulate_lines(raster, lines)
+        raster = simulate(raster, blob)
         assert raster == want, "delta %d does not reproduce its frame" % i
 
 
@@ -298,9 +261,6 @@ def emit_block(base_lines, delta_ranges, all_lines):
     for i, s in enumerate(all_lines):
         out.append('IM$(%d) = "%s"' % (i, s))
     out.append("REM  ---- PICTURE-END")
-    for line in out:
-        assert len(line) <= MAXLINE, "emitted line over %d chars: %r" % (
-            MAXLINE, line)
     return out
 
 
@@ -343,15 +303,15 @@ def main():
     base_lines = chop(base_blob)
     all_lines = list(base_lines)
     delta_ranges = []
-    delta_line_groups = []
+    delta_blobs = []
     for i in range(PHASES):
         blob = encode_delta(frames[i], frames[(i + 1) % PHASES])
+        delta_blobs.append(blob)
         lines = chop(blob)
-        delta_line_groups.append(lines)
         delta_ranges.append((len(all_lines), len(all_lines) + len(lines) - 1))
         all_lines.extend(lines)
-    verify(frames, base_lines, delta_line_groups)
+    verify(frames, base_blob, delta_blobs)
-    dbytes = sum(len(l) for g in delta_line_groups for l in g)
+    dbytes = sum(len(b) for b in delta_blobs)
     print("base %d bytes in %d strings; video %d bytes in %d strings; "
           "%d strings total" %
           (sum(len(s) for s in base_lines), len(base_lines), dbytes,

include/akbasic/runtime.h

@@ -211,12 +211,8 @@ typedef struct akbasic_Runtime
      * not exist relative to the working directory, which is what makes a `.bas`
      * beside its art work from anywhere. Group F's disk verbs will want the
      * same, which is why it is on the runtime rather than in the sprite state.
-     *
-     * Sized to AKBASIC_MAX_SOURCE_PATH_LENGTH, not AKBASIC_MAX_LINE_LENGTH: a
-     * directory is a filesystem path, not a line of BASIC, and the two do not
-     * belong to the same budget.
      */
-    char sourcepath[AKBASIC_MAX_SOURCE_PATH_LENGTH];
+    char sourcepath[AKBASIC_MAX_LINE_LENGTH];
 
     /*
      * The armed interrupts, and the environment the one currently running was
@@ -252,6 +248,11 @@ typedef struct akbasic_Runtime
      */
     int64_t timems;
 
+    /* RND's lazy seed state. The flag distinguishes an unseeded run from a
+     * legitimate LCG state of zero. */
+    int64_t rndseed;
+    bool rndseeded;
+
     /*
      * Set by a branch that has decided the remaining statements on its line
      * belong to the arm it did not take, and cleared at the top of every line.
@@ -369,7 +370,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akbasic_runtime_set_ui(akbasic_Runtime *obj,
  * @param path Path to the program file, or NULL for none.
  * @return `NULL` on success, otherwise an error context owned by the caller.
  * @throws AKERR_NULLPOINTER When `obj` is NULL.
- * @throws AKBASIC_ERR_BOUNDS When the path is longer than AKBASIC_MAX_SOURCE_PATH_LENGTH.
+ * @throws AKBASIC_ERR_BOUNDS When the path is longer than AKBASIC_MAX_LINE_LENGTH.
  */
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_runtime_set_source_path(akbasic_Runtime *obj, const char *path);
 

include/akbasic/symtab.h

@@ -23,17 +23,9 @@
  * serves variables, functions and labels. Capacity is a member; the table is
  * kept below a 75% load factor by construction because `capacity` counts slots
  * and the caller's logical maximum is smaller.
- *
- * 172 rather than the old 256: no caller passes akbasic_symtab_init() anything
- * larger than AKBASIC_MAX_VARIABLES (128), and 172 keeps that under the 75%
- * load factor the comment above promises (128 / 0.75 = 170.7).
- *
- * AKBASIC_SYMTAB_MAX_KEY 24 rather than 64: the longest identifier across
- * examples/breakout and examples/megademo -- variables, DIMmed arrays, labels
- * and DEF FN names alike -- is 11 characters (TITLESCREEN, CLEARPOWERS).
  */
-#define AKBASIC_SYMTAB_MAX_SLOTS	172
+#define AKBASIC_SYMTAB_MAX_SLOTS	256
-#define AKBASIC_SYMTAB_MAX_KEY		24
+#define AKBASIC_SYMTAB_MAX_KEY		64
 
 typedef struct
 {

include/akbasic/types.h

@@ -6,7 +6,6 @@
 #ifndef _AKBASIC_TYPES_H_
 #define _AKBASIC_TYPES_H_
 
-#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 
@@ -28,39 +27,15 @@
 #define AKBASIC_MAX_VALUES		64
 #define AKBASIC_MAX_VARIABLES		128
 
-/*
+/* Whole-runtime pools */
- * Whole-runtime pools.
+#define AKBASIC_MAX_SOURCE_LINES	9999
- *
+#define AKBASIC_MAX_LINE_LENGTH		256
- * AKBASIC_MAX_SOURCE_LINES, AKBASIC_MAX_LINE_LENGTH, AKBASIC_MAX_ARRAY_VALUES,
- * AKBASIC_MAX_ENVIRONMENTS and AKBASIC_MAX_FUNCTIONS were cut from their
- * original values against measurements taken off examples/breakout and
- * examples/megademo, the two most demanding programs this interpreter runs --
- * see the memory-footprint discussion this commit's PR body links. Each is
- * sized at roughly 1.5-2x the peak the reference corpus actually reaches, not
- * at the peak itself.
- *
- * AKBASIC_MAX_LINE_LENGTH in particular follows Commodore BASIC's own 80-column
- * line limit rather than a measurement, which is why sink_stdio.c now refuses a
- * line that fills the buffer with no terminator instead of silently truncating
- * it: at 256 bytes that failure mode was theoretical, and at 80 it is not.
- *
- * AKBASIC_MAX_SOURCE_PATH_LENGTH is its own constant rather than a reuse of
- * AKBASIC_MAX_LINE_LENGTH, which is where it used to come from. `sourcepath`
- * (runtime.h) holds a directory, not a line of BASIC, and the two ideas do not
- * scale together: shrinking the line limit to 80 broke every golden test in
- * this checkout, because this repository's own working directory is deeper
- * than that. PATH_MAX is the actual bound a filesystem path is subject to, so
- * it is the one this borrows.
- */
-#define AKBASIC_MAX_SOURCE_LINES	2048
-#define AKBASIC_MAX_LINE_LENGTH		80	/* Commodore BASIC's own line limit */
-#define AKBASIC_MAX_SOURCE_PATH_LENGTH	PATH_MAX
 #define AKBASIC_MAX_ARRAY_DEPTH		64	/* dimensions per array */
 #define AKBASIC_MAX_ARRAY_ELEMENTS	1024	/* elements in one array */
-#define AKBASIC_MAX_ARRAY_VALUES	2048	/* array elements across all variables */
+#define AKBASIC_MAX_ARRAY_VALUES	4096	/* array elements across all variables */
 #define AKBASIC_MAX_STRING_LENGTH	256	/* see TODO.md 1.2 */
-#define AKBASIC_MAX_ENVIRONMENTS	12	/* new: Go allocated these unbounded */
+#define AKBASIC_MAX_ENVIRONMENTS	32	/* new: Go allocated these unbounded */
-#define AKBASIC_MAX_FUNCTIONS		8	/* new: Go used an unbounded map */
+#define AKBASIC_MAX_FUNCTIONS		64	/* new: Go used an unbounded map */
 #define AKBASIC_MAX_LABELS		64	/* new: Go used an unbounded map */
 /*
  * Leaves a DO/LOOP condition may use. Its own small pool rather than a second

include/akbasic/variable.h

@@ -13,22 +13,12 @@
 
 #include <akerror.h>
 
-#include <akbasic/symtab.h>
 #include <akbasic/types.h>
 #include <akbasic/value.h>
 
 typedef struct
 {
-    /*
+    char name[AKBASIC_MAX_STRING_LENGTH];
-     * Sized to AKBASIC_SYMTAB_MAX_KEY, not AKBASIC_MAX_STRING_LENGTH: this name
-     * only ever gets here by surviving akbasic_symtab_set() first
-     * (akbasic_environment_create() calls it right after this field is
-     * populated), and that call refuses anything AKBASIC_SYMTAB_MAX_KEY
-     * characters or longer with AKBASIC_ERR_BOUNDS. A variable whose name did
-     * not fit could never exist, so the wider buffer was 232 bytes of headroom
-     * nothing could ever put a byte into.
-     */
-    char name[AKBASIC_SYMTAB_MAX_KEY];
     akbasic_Type valuetype;
     akbasic_Value *values;			/** The pool, or `inlinevalue` for a scalar */
     int valuecount;

src/runtime.c

@@ -301,7 +301,7 @@ akerr_ErrorContext *akbasic_runtime_set_source_path(akbasic_Runtime *obj, const
     }
     FAIL_ZERO_RETURN(errctx, (length < sizeof(obj->sourcepath)), AKBASIC_ERR_BOUNDS,
 		     "Program path of %zu characters exceeds the %d character limit",
-		     length, AKBASIC_MAX_SOURCE_PATH_LENGTH - 1);
+		     length, AKBASIC_MAX_LINE_LENGTH - 1);
     PASS(errctx, aksl_memcpy(obj->sourcepath, path, length));
     obj->sourcepath[length] = '\0';
     SUCCEED_RETURN(errctx);

src/runtime_functions.c

@@ -183,6 +183,69 @@ akerr_ErrorContext *akbasic_fn_chr(akbasic_Runtime *obj, akbasic_ASTLeaf *expr,
     SUCCEED_RETURN(errctx);
 }
 
+akerr_ErrorContext *akbasic_fn_asc(akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest)
+{
+    PREPARE_ERROR(errctx);
+    akbasic_Value *arg = NULL;
+    akbasic_Value *out = NULL;
+    const unsigned char *text = NULL;
+    int64_t codepoint = 0;
+
+    (void)lval; (void)rval;
+    PASS(errctx, first_arg(obj, expr, "ASC", NULL, &arg, &out));
+    FAIL_NONZERO_RETURN(errctx, (arg->valuetype != AKBASIC_TYPE_STRING), AKBASIC_ERR_TYPE,
+			"ASC expected a string");
+    FAIL_ZERO_RETURN(errctx, (arg->stringval[0] != '\0'), AKBASIC_ERR_BOUNDS,
+		     "ASC expected a non-empty string");
+
+    /* Decode the first UTF-8 code point, the inverse of CHR's encoder. */
+    text = (const unsigned char *)arg->stringval;
+    if ( text[0] < 0x80 ) {
+	codepoint = text[0];
+    } else if ( (text[0] & 0xE0) == 0xC0 ) {
+	codepoint = ((int64_t)(text[0] & 0x1F) << 6) |
+		    (text[1] & 0x3F);
+    } else if ( (text[0] & 0xF0) == 0xE0 ) {
+	codepoint = ((int64_t)(text[0] & 0x0F) << 12) |
+		    ((int64_t)(text[1] & 0x3F) << 6) |
+		    (text[2] & 0x3F);
+    } else {
+	codepoint = ((int64_t)(text[0] & 0x07) << 18) |
+		    ((int64_t)(text[1] & 0x3F) << 12) |
+		    ((int64_t)(text[2] & 0x3F) << 6) |
+		    (text[3] & 0x3F);
+    }
+    out->valuetype = AKBASIC_TYPE_INTEGER;
+    out->intval = codepoint;
+    *dest = out;
+    SUCCEED_RETURN(errctx);
+}
+
+akerr_ErrorContext *akbasic_fn_rnd(akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest)
+{
+    PREPARE_ERROR(errctx);
+    akbasic_Value *arg = NULL;
+    akbasic_Value *out = NULL;
+    const int64_t modulus = 2147483648;
+
+    (void)lval; (void)rval;
+    PASS(errctx, first_arg(obj, expr, "RND", NULL, &arg, &out));
+    FAIL_NONZERO_RETURN(errctx, (arg->valuetype != AKBASIC_TYPE_INTEGER), AKBASIC_ERR_TYPE,
+			"RND expected an integer");
+    FAIL_ZERO_RETURN(errctx, (arg->intval > 0), AKBASIC_ERR_VALUE,
+		     "RND count %" PRId64 " must be positive", arg->intval);
+
+    if ( !obj->rndseeded ) {
+	obj->rndseed = obj->timems % modulus;
+	obj->rndseeded = true;
+    }
+    obj->rndseed = (obj->rndseed * 1103515245 + 12345) % modulus;
+    out->valuetype = AKBASIC_TYPE_INTEGER;
+    out->intval = (obj->rndseed / 65536) % arg->intval;
+    *dest = out;
+    SUCCEED_RETURN(errctx);
+}
+
 akerr_ErrorContext *akbasic_fn_hex(akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest)
 {
     PREPARE_ERROR(errctx);

src/sink_stdio.c

@@ -74,19 +74,6 @@ static akerr_ErrorContext *stdio_readline(akbasic_TextSink *self, char *dest, si
     if ( *eof ) {
 	SUCCEED_RETURN(errctx);
     }
-    /*
-     * aksl_fgets(3)'s own contract: a full buffer with no trailing newline is
-     * how a caller spots a line longer than the buffer, because the rest of it
-     * is still sitting unread in the stream. Refusing here is what makes that
-     * true -- without it, the unread remainder is picked up by the *next*
-     * readline() as if it were its own statement, which does not fail, it just
-     * runs the wrong program. AKBASIC_MAX_LINE_LENGTH is small enough now that
-     * this is not a hypothetical: examples/breakout's own longest line used to
-     * clear the old 256-byte ceiling by more than half.
-     */
-    FAIL_NONZERO_RETURN(errctx, (used == len - 1 && dest[used - 1] != '\n' && dest[used - 1] != '\r'),
-			AKBASIC_ERR_BOUNDS,
-			"Source line exceeds the %zu character limit", len - 1);
     /*
      * Strip the line terminator. The scanner treats \r and \n as end-of-line
      * anyway, but leaving them on would make a stored source line differ from

src/verbs.c

@@ -37,6 +37,7 @@ static const akbasic_Verb VERBS[] = {
     { "ABS",          AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_abs },
     { "AND",          AKBASIC_TOK_AND,                  -1, NULL,                  NULL },
     { "APPEND",       AKBASIC_TOK_COMMAND,              -1, akbasic_parse_arglist, akbasic_cmd_append },
+    { "ASC",          AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_asc },
     { "ATN",          AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_atn },
     { "AUTO",         AKBASIC_TOK_COMMAND_IMMEDIATE,    -1, NULL,                  akbasic_cmd_auto },
     { "BACKUP",       AKBASIC_TOK_COMMAND,              -1, akbasic_parse_optional_arglist, akbasic_cmd_backup },
@@ -146,6 +147,7 @@ static const akbasic_Verb VERBS[] = {
     { "RGR",          AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_rgr },
     { "RIGHT",        AKBASIC_TOK_FUNCTION,              2, NULL,                  akbasic_fn_right },
     { "RMENU",        AKBASIC_TOK_FUNCTION,              2, NULL,                  akbasic_fn_rmenu },
+    { "RND",          AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_rnd },
     { "RSPCOLOR",     AKBASIC_TOK_FUNCTION,              1, NULL,                  akbasic_fn_rspcolor },
     { "RSPHIT",       AKBASIC_TOK_FUNCTION,              2, NULL,                  akbasic_fn_rsphit },
     { "RSPPOS",       AKBASIC_TOK_FUNCTION,              2, NULL,                  akbasic_fn_rsppos },

src/verbs.h

@@ -140,6 +140,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akbasic_cmd_stop(struct akbasic_Runtime *obj,
 
 /* Function handlers -- src/runtime_functions.c */
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_abs(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
+akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_asc(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_atn(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_chr(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_cos(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
@@ -154,6 +155,7 @@ akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_peek(struct akbasic_Runtime *obj,
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_pointer(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_pointervar(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_rad(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
+akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_rnd(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_right(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_sgn(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);
 akerr_ErrorContext AKERR_NOIGNORE *akbasic_fn_shl(struct akbasic_Runtime *obj, akbasic_ASTLeaf *expr, akbasic_Value *lval, akbasic_Value *rval, akbasic_Value **dest);

tests/language/arrays_in_parameter_lists.bas

@@ -1,6 +1,6 @@
 10 REM An array reference used as a function argument, and as one of several.
 20 REM An identifier's subscript list used to hang off .right, which is also
-30 REM where an argument list chains its arguments; the arity counter walked
+30 REM where an argument list chains its arguments -- so the arity counter walked
 40 REM straight into the subscripts and refused the call. TODO.md section 4.
 50 DIM C#(4)
 60 C#(1) = -9

tests/language/audio/filter_refused.bas

@@ -1,6 +1,6 @@
-10 REM FILTER has no device capability; akgl_audio_* synthesises and mixes but
+10 REM FILTER has no device capability behind it -- akgl_audio_* synthesises and
-20 REM has no filter stage, and SDL3 supplies no primitive to build one from.
+20 REM mixes but has no filter stage, and SDL3 supplies no primitive to build one
-30 REM It is refused rather than silently ignored, so a program that asked
+30 REM from. It is refused rather than silently ignored, so a program that asked
 40 REM for a low-pass finds out it did not get one.
 50 PRINT "BEFORE"
 60 FILTER 1000, 1, 0, 0, 5

tests/language/audio/no_device.bas

@@ -1,4 +1,4 @@
-10 REM The standalone driver lends the script no audio device. ENVELOPE, VOL,
+10 REM The standalone driver lends the script no audio device. ENVELOPE, VOL and
 20 REM TEMPO only change interpreter state, so they work regardless; SOUND and
 30 REM PLAY need the device and must name themselves when there is none.
 40 ENVELOPE 1, 5, 9, 12, 2

tests/language/functions/asc.bas

@@ -0,0 +1,3 @@
+10 PRINT "97 : " + ASC("a")
+20 PRINT "65 : " + ASC("A")
+30 PRINT "64 : " + ASC("@")

tests/language/functions/asc.txt

@@ -0,0 +1,3 @@
+97 : 97
+65 : 65
+64 : 64

tests/language/functions/recursion.bas

@@ -1,6 +1,6 @@
-10 REM A DEF call takes one environment from the pool, exactly as
+10 REM A DEF call takes its environment from the pool, one per call, exactly as
 20 REM GOSUB does. It used to be owned by the funcdef and reset on every call,
-30 REM which cost two silent defects: calls in one expression shared a slot,
+30 REM which cost two silent defects: two calls in one expression shared a slot,
 40 REM and recursion never came back at all.
 50 DEF FACT(N#)
 60 IF N# <= 1 THEN RETURN 1
@@ -15,9 +15,9 @@
 150 DEF DBL(N#) = N# * 2
 160 PRINT DBL(10) + DBL(1)
 170 PRINT DBL(1) + DBL(10) + DBL(100)
-180 REM Depth answers to the environment pool, so runaway recursion reports
+180 REM Depth answers to the environment pool now, so runaway recursion reports
-190 REM "Environment pool exhausted" rather than hanging. It is not exercised
+190 REM "Environment pool exhausted" rather than hanging. It is not exercised here
-200 REM here because the failed statement still prints junk afterwards;
+200 REM because the statement containing a failed call still prints a junk value
-210 REM this is a separate defect in TODO.md, and one this golden file
+210 REM afterwards -- a separate, pre-existing defect recorded in TODO.md, and one
-220 REM would pin if it went in. tests/user_functions.c asserts
+220 REM this golden file would pin if it went in. tests/user_functions.c asserts
 230 REM the message instead.

tests/language/graphics/argument_errors.bas

@@ -1,4 +1,4 @@
-10 REM A range check reported through the driver, end to end. The program
+10 REM A range check reported through the driver, end to end. The program stops
 20 REM at the first error, so this file covers one; the rest of the checks are
 30 REM asserted in tests/graphics_verbs.c against the recording backend.
 40 PRINT "BEFORE"

tests/language/graphics/no_device.bas

@@ -1,5 +1,5 @@
 10 REM The standalone driver lends the script no graphics device.
-20 REM COLOR, LOCATE and SCALE touch interpreter state and must still work.
+20 REM COLOR, LOCATE and SCALE only touch interpreter state and must still work.
 30 COLOR 1, 3
 40 LOCATE 40, 50
 50 SCALE 1, 640, 400

tests/language/housekeeping/verbs.bas

@@ -1,5 +1,5 @@
-10 REM Group B: housekeeping verbs. None is in the Go reference --
+10 REM Group B: the housekeeping verbs. None of these is in the Go reference --
-20 REM they are on its unimplemented list -- so each meaning here is
+20 REM they are on its own unimplemented list -- so what each one means here is
 30 REM a decision, recorded in src/runtime_housekeeping.c beside the verb.
 40 A# = 1 : B# = 2
 50 PRINT A# : PRINT B#
@@ -11,7 +11,7 @@
 110 P#(2) = 7 : Q#(2) = 9
 120 SWAP P#, Q#
 130 PRINT P#(2) : PRINT Q#(2)
-140 REM TRON prints each line number inline, as a C128 does.
+140 REM TRON prints each line number inline before the line runs, as a C128 does.
 150 TRON
 160 PRINT "TRACED"
 170 TROFF

tests/language/numeric/octal_literal.bas

@@ -1,7 +1,7 @@
-10 REM A leading zero is padding, not a radix. The reference selected base 8
+10 REM A leading zero is padding, not a radix. The reference selects base 8 for
-20 REM for lexemes starting with 0; 010 printed 8 and 08 was a parse error --
+20 REM any lexeme starting with 0, so 010 printed 8 and 08 was a parse error --
-30 REM TODO.md section 6 item 10 is fixed; Commodore BASIC has no octal.
+30 REM TODO.md section 6 item 10, fixed. Commodore BASIC has no octal literals.
-40 REM 0x is the one prefix that changes the base, and now reaches the scanner
+40 REM 0x is the one prefix that changes the base, and it now reaches the scanner
 50 REM whole: that was section 6 item 15.
 60 PRINT 010
 70 PRINT 08

tests/language/numeric/truth_value_arithmetic.bas

@@ -1,12 +1,12 @@
 10 REM A truth value carries its payload in boolvalue, not floatval. The three
 20 REM numeric operators were `if ( INTEGER ) ... else <treat as float>`, and
-30 REM that else was a catch-all, not a float branch -- so a truth value
+30 REM that else was a catch-all rather than a float branch -- so a truth value
 40 REM on the LEFT computed 0 - 1 into a field nothing reads, kept its BOOLEAN
 50 REM type, and printed `true` instead of -2. Silent, and wrong twice over.
 60 A# = 1
 70 PRINT (A# == 1)
-80 REM On the RIGHT it stays legal and stays -1, the same property that
+80 REM On the RIGHT it stays legal and stays -1, which is the same property that
-90 REM lets AND and OR act as logical operators. Refusing it would have
+90 REM lets AND and OR double as logical operators. Refusing it here would have
 100 REM broken every condition in the language.
 110 PRINT 5 - (A# == 1)
 120 PRINT 5 * (A# == 1)

tests/language/statements/multiple_per_line.bas

@@ -1,11 +1,11 @@
-10 REM Statements separated by colons. The COLON token existed from the start;
+10 REM Statements separated by colons. The COLON token existed from the start of
-20 REM nothing consumed it, so a line could hold only one statement.
+20 REM the port and nothing consumed it, so a line could hold only one statement.
 30 PRINT "A" : PRINT "B"
 40 A# = 1 : B# = 2 : PRINT A# + B#
-50 REM Empty statements are valid: a trailing separator or runs of them.
+50 REM An empty statement is not an error: a trailing separator, or a run of them.
 60 PRINT "C" :
 70 PRINT "D" :: PRINT "E"
-80 REM Everything after THEN belongs to the condition, as in BASIC 7.0, and is
+80 REM Everything after THEN belongs to the condition, which is BASIC 7.0 and is
 90 REM not something the reference had an opinion about -- it never got here.
 100 IF 1 == 1 THEN PRINT "TRUE-1" : PRINT "TRUE-2"
 110 IF 1 == 0 THEN PRINT "NEVER-1" : PRINT "NEVER-2"

tests/language/structures/missing_field.bas

@@ -1,5 +1,5 @@
-10 REM A field name is checked against the closed set the program declared;
+10 REM A field name is checked against a closed set the program declared, which
-20 REM this is the one thing whose valid spellings are written down.
+20 REM is the one thing in this language whose valid spellings are written down.
 30 REM A misspelled *variable* is still silent -- see the last two lines.
 40 TYPE RECT
 50   W#

tests/language/structures/parameters.bas

@@ -17,7 +17,7 @@
 170 RETURN B@.W#
 180 PRINT WIDEN(A@)
 190 PRINT A@.W#
-200 REM To change one on purpose, pass a pointer. Assignment copies its
+200 REM To change one on purpose, pass a pointer. Assignment copies a pointer's
 210 REM reference, so the callee is looking at the caller's own record.
 220 DIM Q@ AS PTR TO CRATE
 230 POINT Q@ AT A@
@@ -37,7 +37,7 @@
 370 N2@.COUNT# = 20
 380 POINT N1@.TAIL@ AT N2@
 390 DEF TOTAL(P@ AS PTR TO NODE)
-395 REM A pointer is true when it points at something, so a walk knows
+395 REM A pointer is true when it points at something, which is how a walk knows
 396 REM where the list ends. NOT is the bitwise operator here, so the test is
 397 REM written the positive way round.
 400 IF P@->TAIL@ THEN RETURN P@->COUNT# + TOTAL(P@->TAIL@)

tests/language/structures/records.bas

@@ -1,4 +1,4 @@
-10 REM A TYPE declares its fields; each takes its type from its own suffix,
+10 REM A TYPE declares its fields; each takes its own type from its own suffix,
 20 REM which is the same rule every other name in this language follows.
 30 TYPE COORD
 40   X#

tests/language/structures/reserved_names.bas

@@ -1,6 +1,6 @@
 10 REM A type name and a field name are bare words, and so is every verb, so
 20 REM they share a namespace whether we like it or not. Both are refused with
-30 REM the scanner applies the same rule to variable names -- and a type
+30 REM the same rule the scanner already applies to variable names -- and a type
 40 REM name is refused by the prescan, which can say so plainly rather than
 50 REM leaving the parser to report "Expected expression or literal".
 60 TYPE POINT

tests/reference/language/flowcontrol/nestedforloopwaitingforcommand.bas

@@ -1,6 +1,6 @@
 10 REM This shows the waitingForCommand utility in the BasicEnvironment
 11 REM when we have a nested for loop. The inner loop SHOULD execute, but
-12 REM the outer loop should NOT execute; neither loop should execute.
+12 REM the outer loop should NOT execute. Therefore, neither loop should execute.
 20 FOR I# = 1 TO 0
 25 FOR J# = 2 TO 4
 30 PRINT "waitingForCommand FAILS if this is seen"

tests/reference/language/functions/mod.bas

@@ -1,6 +1,6 @@
 10 PRINT MOD(10, 3)
 20 PRINT MOD(12, 5)
 30 PRINT MOD(4, 2)
-40 REM MOD() ONLY WORKS WITH INTEGERS; FLOATING POINT RESULTS ARE UNRELIABLE
+40 REM MOD() ONLY WORKS WITH INTEGERS - RESULTS WITH FLOATING POINT ARE UNRELIABLE
 50 REM PRINT MOD(1.2, 0.4)
 60 REM THERE IS NO ERROR THROWN HERE. JUST DONT DO IT.

tests/runtime_evaluate.c

@@ -162,6 +162,26 @@ int main(void)
     expect_int("A# = INSTR(\"HELLO\", \"LL\")", 2);
     expect_int("A# = INSTR(\"HELLO\", \"ZZ\")", -1);
 
+    /* RND auto-seeds from host time and follows the documented LCG. */
+    HARNESS_RUNTIME.rndseeded = false;
+    TEST_REQUIRE_OK(akbasic_runtime_settime(&HARNESS_RUNTIME, 12345));
+    expect_int("A# = RND(6)", 0);
+    expect_int("A# = RND(6)", 4);
+    expect_int("A# = RND(6)", 1);
+    expect_int("A# = RND(6)", 0);
+    expect_int("A# = RND(6)", 1);
+    expect_int("A# = RND(1)", 0);
+    TEST_REQUIRE_STATUS(eval_line("A# = RND(0)", &out), AKBASIC_ERR_VALUE);
+    TEST_REQUIRE_STATUS(eval_line("A# = RND(-1)", &out), AKBASIC_ERR_VALUE);
+    TEST_REQUIRE_STATUS(eval_line("A# = RND(\"x\")", &out), AKBASIC_ERR_TYPE);
+
+    /* ASC is the inverse of CHR for ASCII and non-ASCII code points. */
+    expect_int("A# = ASC(CHR(97))", 97);
+    expect_int("A# = ASC(\"A\")", 65);
+    expect_int("A# = ASC(CHR(8364))", 8364);
+    TEST_REQUIRE_STATUS(eval_line("A# = ASC(\"\")", &out), AKBASIC_ERR_BOUNDS);
+    TEST_REQUIRE_STATUS(eval_line("A# = ASC(65)", &out), AKBASIC_ERR_TYPE);
+
     /* An unknown verb is diagnosed rather than silently ignored. */
     TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
     TEST_REQUIRE_STATUS(akbasic_runtime_evaluate(&HARNESS_RUNTIME, NULL, &out),

tests/value_pool.c

@@ -97,9 +97,9 @@ static void test_scoped_loop_counter_costs_nothing(void)
 /**
  * @brief The pool is genuinely untouched, not merely large enough.
  *
- * Two hundred scope entries and then the pool's *entire* width -- two arrays,
+ * Two hundred scope entries and then the pool's *entire* width -- four arrays,
  * because AKBASIC_MAX_ARRAY_ELEMENTS caps any one of them at 1024 while the pool
- * holds 2048. One leaked slot and the second `DIM` has nowhere to go, which
+ * holds 4096. One leaked slot and the fourth `DIM` has nowhere to go, which
  * makes this the sharpest of the three and by far the cheapest: the two above
  * prove a program finishes, this proves nothing at all was spent. The long ones
  * stay because they are the shape the defect was found in.
@@ -111,8 +111,10 @@ static void test_pool_is_untouched_by_scopes(void)
 				"30 NEXT T#\n"
 				"40 DIM A#(1024)\n"
 				"50 DIM B#(1024)\n"
-				"70 B#(1023) = 7\n"
+				"60 DIM C#(1024)\n"
-				"90 PRINT B#(1023)\n"
+				"70 DIM D#(1024)\n"
+				"80 D#(1023) = 7\n"
+				"90 PRINT D#(1023)\n"
 				"100 END\n"
 				"110 LABEL SUBA\n"
 				"120 LOC# = 1\n"