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/16-structures.md

@@ -50,7 +50,7 @@ nothing would say which type it is.
 ```
 
 ```output
-? 10 : PARSE ERROR TYPE POINT: POINT is a reserved word and cannot name a type
+? 40 : PARSE ERROR TYPE POINT: POINT is a reserved word and cannot name a type
 
 ```
 

docs/17-tutorial-breakout.md

@@ -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$ = ""

include/akbasic/runtime.h

@@ -252,6 +252,11 @@ 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.

src/data.c

@@ -160,21 +160,14 @@ akerr_ErrorContext *akbasic_data_scan(akbasic_Runtime *obj)
 {
     PREPARE_ERROR(errctx);
     int64_t i = 0;
-    int64_t entry = 0;
 
     FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL runtime in data_scan");
-    FAIL_ZERO_RETURN(errctx, (obj->environment != NULL), AKERR_NULLPOINTER,
-		     "Runtime has no environment; call akbasic_runtime_init() first");
-    entry = obj->environment->lineno;
     PASS(errctx, akbasic_data_state_init(&obj->data_state));
     for ( i = 0; i < AKBASIC_MAX_SOURCE_LINES; i++ ) {
 	if ( obj->source[i].code[0] != '\0' ) {
-	    /* Keep BASIC's error prefix on the source line being prescanned. */
-	    obj->environment->lineno = i;
 	    PASS(errctx, scan_line(&obj->data_state, obj->source[i].code, i));
 	}
     }
-    obj->environment->lineno = entry;
     SUCCEED_RETURN(errctx);
 }
 

src/runtime.c

@@ -1600,22 +1600,17 @@ akerr_ErrorContext *akbasic_runtime_scan_labels(akbasic_Runtime *obj)
     PREPARE_ERROR(errctx);
     akbasic_Environment *root = NULL;
     int64_t i = 0;
-    int64_t entry = 0;
 
     FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL runtime in scan_labels");
     FAIL_ZERO_RETURN(errctx, (obj->environment != NULL), AKERR_NULLPOINTER,
 		     "Runtime has no environment; call akbasic_runtime_init() first");
     for ( root = obj->environment; root->parent != NULL; root = root->parent ) {
     }
-    entry = obj->environment->lineno;
     for ( i = 0; i < AKBASIC_MAX_SOURCE_LINES; i++ ) {
 	if ( obj->source[i].code[0] != '\0' ) {
-	    /* Keep BASIC's error prefix on the source line being prescanned. */
-	    obj->environment->lineno = i;
 	    PASS(errctx, scan_line_labels(root, obj->source[i].code, i));
 	}
     }
-    obj->environment->lineno = entry;
     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/structtype.c

@@ -260,13 +260,11 @@ static akerr_ErrorContext *scan_names(akbasic_Runtime *obj)
     size_t namelen = 0;
     bool matched = false;
     const akbasic_Verb *verb = NULL;
-    int64_t entry = obj->environment->lineno;
 
     for ( i = 0; i < AKBASIC_MAX_SOURCE_LINES; i++ ) {
 	if ( obj->source[i].code[0] == '\0' ) {
 	    continue;
 	}
-	obj->environment->lineno = i;
 	cursor = next_word(skip_lineno(obj->source[i].code), word, sizeof(word));
 
 	PASS(errctx, word_is(word, "END", &matched));
@@ -329,7 +327,6 @@ static akerr_ErrorContext *scan_names(akbasic_Runtime *obj)
 
     FAIL_NONZERO_RETURN(errctx, (open >= 0), AKBASIC_ERR_SYNTAX,
 			"TYPE %s is never closed with END TYPE", table->types[open >= 0 ? open : 0].name);
-    obj->environment->lineno = entry;
     SUCCEED_RETURN(errctx);
 }
 
@@ -443,7 +440,7 @@ static akerr_ErrorContext *parse_field(akbasic_StructTypeTable *table, akbasic_S
  * each other by value, which has no finite size. That is the diagnosis rather
  * than a stack overflow later.
  */
-static akerr_ErrorContext *resolve_sizes(akbasic_Runtime *runtime, akbasic_StructTypeTable *table)
+static akerr_ErrorContext *resolve_sizes(akbasic_StructTypeTable *table)
 {
     PREPARE_ERROR(errctx);
     bool progress = true;
@@ -480,7 +477,6 @@ static akerr_ErrorContext *resolve_sizes(akbasic_Runtime *runtime, akbasic_Struc
     }
 
     for ( i = 0; i < table->count; i++ ) {
-	runtime->environment->lineno = table->types[i].firstline;
 	FAIL_NONZERO_RETURN(errctx, (table->types[i].slotcount < 0), AKBASIC_ERR_VALUE,
 			    "TYPE %s contains itself by value, so it has no size. "
 			    "A type may only refer to itself through PTR TO",
@@ -497,13 +493,9 @@ akerr_ErrorContext *akbasic_structtype_scan(akbasic_Runtime *obj)
     akbasic_StructTypeTable *table = NULL;
     int64_t i = 0;
     int t = 0;
-    int64_t entry = 0;
 
     FAIL_ZERO_RETURN(errctx, (obj != NULL), AKERR_NULLPOINTER, "NULL runtime in structtype scan");
-    FAIL_ZERO_RETURN(errctx, (obj->environment != NULL), AKERR_NULLPOINTER,
-		     "Runtime has no environment; call akbasic_runtime_init() first");
     table = &obj->structtypes;
-    entry = obj->environment->lineno;
 
     /*
      * Drop what the *script* declared and keep what the *host* registered.
@@ -533,12 +525,10 @@ akerr_ErrorContext *akbasic_structtype_scan(akbasic_Runtime *obj)
 	    if ( obj->source[i].code[0] == '\0' ) {
 		continue;
 	    }
-	    obj->environment->lineno = i;
 	    PASS(errctx, parse_field(table, type, obj->source[i].code, i));
 	}
     }
 
-    PASS(errctx, resolve_sizes(obj, table));
+    PASS(errctx, resolve_sizes(table));
-    obj->environment->lineno = entry;
     SUCCEED_RETURN(errctx);
 }

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/interrupts.c

@@ -16,8 +16,6 @@
  * below.
  */
 
-#include <stdio.h>
-
 #include "harness.h"
 
 /**
@@ -343,28 +341,6 @@ static akerr_ErrorContext AKERR_NOIGNORE *test_prescan_boundaries(void)
     SUCCEED_RETURN(errctx);
 }
 
-/** @brief A full label table reports the line whose label could not be filed. */
-static void test_label_prescan_error_line(void)
-{
-    char source[4096] = "";
-    size_t used = 0;
-    int i = 0;
-
-    for ( i = 1; i <= AKBASIC_MAX_LABELS + 1; i++ ) {
-	used += (size_t)snprintf(source + used, sizeof(source) - used,
-				"%d LABEL L%d\n", i, i);
-    }
-    (void)snprintf(source + used, sizeof(source) - used, "100 PRINT 1\n");
-
-    TEST_REQUIRE_OK(harness_start(NULL));
-    TEST_REQUIRE_OK(akbasic_runtime_load(&HARNESS_RUNTIME, source));
-    TEST_REQUIRE_OK(akbasic_runtime_start(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
-    TEST_REQUIRE(strstr(HARNESS_OUTPUT, "? 65 : PARSE ERROR") != NULL,
-		 "a full label table should report its source line, got \"%s\"",
-		 HARNESS_OUTPUT);
-    harness_stop();
-}
-
 int main(void)
 {
     PREPARE_ERROR(errctx);
@@ -379,7 +355,6 @@ int main(void)
 	CATCH(errctx, test_undefined_label_is_reported());
 	CATCH(errctx, test_arm_refusals());
 	CATCH(errctx, test_prescan_boundaries());
-	test_label_prescan_error_line();
     } CLEANUP {
     } PROCESS(errctx) {
     } HANDLE_DEFAULT(errctx) {

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/structures/reserved_names.txt

@@ -1,2 +1,2 @@
-? 60 : PARSE ERROR TYPE POINT: POINT is a reserved word and cannot name a type
+? 90 : PARSE ERROR TYPE POINT: POINT is a reserved word and cannot name a type
 

tests/read_data.c

@@ -8,7 +8,6 @@
  * TODO.md section 6.
  */
 
-#include <stdio.h>
 #include <string.h>
 
 #include <akbasic/error.h>
@@ -175,34 +174,6 @@ static void test_colon_ends_data(void)
     harness_stop();
 }
 
-/** @brief DATA overflow reports the line where the item limit was crossed. */
-static void test_data_prescan_error_line(void)
-{
-    char source[4096] = "";
-    size_t used = 0;
-    int line = 0;
-    int item = 0;
-
-    for ( line = 1; line <= 34; line++ ) {
-	used += (size_t)snprintf(source + used, sizeof(source) - used, "%d DATA ", line);
-	for ( item = 0; item < 15; item++ ) {
-	    used += (size_t)snprintf(source + used, sizeof(source) - used,
-				      "%s1", (item == 0 ? "" : ","));
-	}
-	used += (size_t)snprintf(source + used, sizeof(source) - used, "\n");
-    }
-	used += (size_t)snprintf(source + used, sizeof(source) - used, "100 DATA 1,1\n");
-	(void)snprintf(source + used, sizeof(source) - used, "101 DATA 1\n200 PRINT 1\n");
-
-    TEST_REQUIRE_OK(harness_start(NULL));
-    TEST_REQUIRE_OK(akbasic_runtime_load(&HARNESS_RUNTIME, source));
-    TEST_REQUIRE_OK(akbasic_runtime_start(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
-	TEST_REQUIRE(strstr(HARNESS_OUTPUT, "? 101 : PARSE ERROR") != NULL,
-		 "DATA overflow should report its source line, got \"%s\"",
-		 HARNESS_OUTPUT);
-    harness_stop();
-}
-
 /** @brief A float item fills a float variable with its fractional part intact. */
 static void test_float_items(void)
 {
@@ -256,7 +227,6 @@ int main(void)
     test_type_mismatch();
     test_quoted_items();
     test_colon_ends_data();
-	test_data_prescan_error_line();
     test_float_items();
     test_negative_items();
     return akbasic_test_failures;

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/struct_types.c

@@ -218,22 +218,6 @@ static void test_declaration_errors_are_basic_errors(void)
     }
 }
 
-/** @brief A field declaration error reports the field's source line. */
-static void test_type_prescan_error_line(void)
-{
-    TEST_REQUIRE_OK(harness_start(NULL));
-    TEST_REQUIRE_OK(akbasic_runtime_load(&HARNESS_RUNTIME,
-					 "10 TYPE RECT\n"
-					 "20 W# EXTRA\n"
-					 "30 END TYPE\n"
-					 "40 PRINT 1\n"));
-    TEST_REQUIRE_OK(akbasic_runtime_start(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
-    TEST_REQUIRE(strstr(HARNESS_OUTPUT, "? 20 : PARSE ERROR") != NULL,
-		 "TYPE prescan should report its source line, got \"%s\"",
-		 HARNESS_OUTPUT);
-    harness_stop();
-}
-
 /**
  * @brief An over-long type or field name is refused, not silently trimmed.
  *
@@ -286,7 +270,6 @@ int main(void)
     test_missing_field_lists_the_others();
     test_self_by_value_refused();
     test_declaration_errors_are_basic_errors();
-    test_type_prescan_error_line();
     test_long_names_are_refused();
 
     return akbasic_test_failures;