- Added string strip methods lstrip and rstrip

- Fixed the tokenizer to chomp whitespace from left and right of tokens
- Fixed the tokenizer so it returns reserved symbols not just constants and expressions
- Added some tests for the basic tokenizer and parser
- Started working on structures to allow the basic interpreter to store lines in memory

README.md

@@ -22,22 +22,19 @@ Currently the BASIC only understands simple arithmetic expressions. But this wil
 How can I run it?
 =====
 
-You have to build it to
- run it. To build it, you need:
+You have to build it to run it. To build it, you need:
 
-* An x86 computer with a floppy drive (or the bochs emulator)
 * bcc (bruce's c compiler - check your OS's package repositories)
 * nasm
 * gnu make
 * ld86, objdump86, as86
 
-To run it, you can use any x86 emulator that can boot a floppy image, but the makefile assumes you have 'bochs' installed.
+To run it, you need either an x86 computer with a floppy drive (or the bochs emulator. For emulation you can use any x86 emulator that can boot a floppy image, but the makefile assumes you have 'bochs' installed.
 
     make clean run
 
 This will rebuild all of the sources and fire up the bochs emulator. Have fun.
 
-
 Developing & Testing
 =======
 

src/basic.c

@@ -21,6 +21,7 @@ char *_tokenize(char *ptr, char *token)
 {
   char *orig = NULL;
   char *tokenptr = NULL;
+  char tmpbuff[256];
   int len = 0;
   int numtokens = 0;
   int i = 0;
@@ -28,6 +29,7 @@ char *_tokenize(char *ptr, char *token)
   if ( ptr == NULL || token == NULL ) {
     return NULL;
   }
+  memset((char *)&tmpbuff, 0x00, 256);
   if ( _tokenizer_prev == ptr ) {
     ptr = _tokenizer_prev_next;
   }
@@ -39,6 +41,10 @@ char *_tokenize(char *ptr, char *token)
     tokenptr = token;
     for ( i = 0 ; i < numtokens; i++) {
       if ( *ptr == *(tokenptr + i)) {
+        if ( len == 0 ) {
+          len = 1;
+          ptr += 1;
+        }
         goto _tokenize_copy;
       }      
     }
@@ -49,10 +55,11 @@ _tokenize_copy:
   if ( len > BASIC_TOKENIZER_MAX_LENGTH ) {
     basic_errno = BASIC_ERR_SYNTAX_TOKEN_LENGTH;
     return NULL;
-  } else if ( len == 0 ) {
-    return NULL;
   }
   memcpy((void *)&_tokenizer_value, (void *)orig, len);
+  lstrip((char *)&_tokenizer_value, (char *)&tmpbuff, " ");
+  rstrip((char *)&tmpbuff, (char *)&_tokenizer_value, " ");
+  
   _tokenizer_prev_next = (ptr + 1);
   return ptr;
 }
@@ -149,6 +156,7 @@ int basic_solve_expr(struct basic_expr *expr, struct basic_variable *result)
 struct basic_expr *basic_parse_expr(char *expbuf)
 {
   struct basic_expr *ret = &math_expressions[0];
+  char *token = NULL;
   char flags = 0;
   /*char *subptr = 0;*/
 
@@ -157,35 +165,37 @@ struct basic_expr *basic_parse_expr(char *expbuf)
 
   while ( *expbuf != '\0' ) {
     if ( *expbuf == ' ' ) {
-      expbuf += sizeof(char);
+      expbuf += 1;
       continue;
-    } else if ( isdigit(*expbuf) == 1 ) {
+    }
+
+    expbuf = _tokenize(expbuf, BASIC_TOKENIZER_TOKENS);
+    token = _token_get();
+    if ( isdigit(*token) == 1 ) {
       if ( (ret->type == 0) && (flags & BASIC_FOUND_LVAL) == BASIC_FOUND_LVAL ) {
 	      basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_LVALUES;
 	      return NULL;
       } else if ( ret->type == 0x0 ) {
-        expbuf = _tokenize(expbuf, BASIC_TOKENIZER_TOKENS);
-        ret->lval.i = atoi(_token_get());
+        ret->lval.i = atoi(token);
         ret->lval_type = BASIC_LVAL_CONST;
-        flags = (flags + BASIC_FOUND_LVAL);
+        flags = (flags | BASIC_FOUND_LVAL);
       } else if ( ret->type != 0x0 && ((flags & BASIC_FOUND_RVAL) == BASIC_FOUND_RVAL)) {
         basic_errno = BASIC_ERR_SYNTAX_MULTIPLE_RVALUES;
         return NULL;
       } else if ( ret->type != 0x0 ) {
-        expbuf = _tokenize(expbuf, BASIC_TOKENIZER_TOKENS);
-        ret->rval.i = atoi(_token_get());
+        ret->rval.i = atoi(token);
         ret->rval_type = BASIC_RVAL_CONST;
       }
-    } else if ( ret->type == 0x0 ) {
-      if ( *expbuf == '+' ) {
+    } else if ( token != NULL && ret->type == 0x0 ) {
+      if ( *token == '+' ) {
       	ret->type = BASIC_OPTP_ADD;
-      } else if ( *expbuf == '*' ) {
+      } else if ( *token == '*' ) {
 	      ret->type = BASIC_OPTP_MUL;
-      } else if ( *expbuf == '-' ) {
+      } else if ( *token == '-' ) {
 	      ret->type = BASIC_OPTP_SUB;
-      } else if ( *expbuf == '/' ) {
+      } else if ( *token == '/' ) {
 	      ret->type = BASIC_OPTP_DIV;
-      } else if ( *expbuf == '%' ) {
+      } else if ( *token == '%' ) {
 	      ret->type = BASIC_OPTP_MOD;
       } else {
 	      basic_errno = BASIC_ERR_SYNTAX_GENERAL;
@@ -195,7 +205,6 @@ struct basic_expr *basic_parse_expr(char *expbuf)
       basic_errno = BASIC_ERR_SYNTAX_GENERAL;
       return NULL;
     }
-    expbuf += sizeof(char);
   }
   return ret;
 }
@@ -216,7 +225,7 @@ void basic_print_var(struct basic_variable *var)
   }
 }
 
-void basic_repl(void)
+void basic_repl(basic_program *program)
 {
   char keybuff[512];
   char outbuff[128];
@@ -244,6 +253,7 @@ void basic_repl(void)
     if ( _cgets((char *)&keybuff) != NULL ) {
       _cputs("\n");
 
+      /* Evaluate */
       expr = basic_parse_expr((char *)&keybuff);
       if ( expr == NULL ) {
         _cputs("Error: ");
@@ -254,7 +264,6 @@ void basic_repl(void)
         continue;
       }
 
-      /* Evaluate */
       basic_solve_expr(expr, &result);
       if ( basic_errno != 0 ) {
         _cputs("Error: ");
@@ -262,6 +271,7 @@ void basic_repl(void)
         _cputs((char *)&decimal);
         _cputs("\n");
       } else {
+        /* Print */
 	      basic_print_var(&result);
       }
     }

src/basic.h

@@ -30,7 +30,7 @@
 #define BASIC_ERR_INTERNAL_UNIMPLEMENTED 9
 #define BASIC_ERR_MATH_DBZ 10
 
-#define BASIC_TOKENIZER_TOKENS " +-/%*="
+#define BASIC_TOKENIZER_TOKENS "+-/%*="
 #define BASIC_TOKENIZER_MAX_LENGTH 512
 #define BASIC_VARNAME_MAX_LENGTH 16
 
@@ -67,11 +67,25 @@ struct basic_variable {
 };
 typedef struct basic_variable basic_variable;
 
+struct basic_line {
+  int lineno;
+  char content[256];
+  struct basic_line *nextline;
+};
+typedef struct basic_line basic_line;
+
+struct basic_program {
+  char name[128];
+  basic_line *first;
+};
+typedef struct basic_program basic_program;
+
 #define BASIC_CONST_TRUE 1
 #define BASIC_CONST_FALSE 0
 
 extern int basic_errno;
 
-void basic_repl(void);
+void basic_repl(basic_program *program);
+basic_expr *basic_parse_expr(char *);
 
 #endif /* _BASIC_H_ */

src/kernel.c

@@ -1,8 +1,10 @@
 #include "screen.h"
 #include "string.h"
 #include "conio.h"
+#include "basic.h"
 
 void main(void)
 {
-  basic_repl();
+  basic_program program;
+  basic_repl(&program);
 }

src/string.c

@@ -81,3 +81,59 @@ int strcmp(char *s1, char *s2)
 
   return 0;
 }
+
+int lstrip(char *s1, char *s2, char *strip)
+{
+  int stripped = 0;
+  char *stripptr = strip;
+  if ( s1 == NULL || s2 == NULL || strip == NULL ) {
+    return 0;
+  }
+  while ( *s1 != 0 ) {
+    if ( stripptr != NULL ) {
+      for ( stripptr = strip; *stripptr != 0; stripptr += 1) {
+        if ( *s1 == *stripptr ) {
+          stripped += 1;
+          goto _lstrip_outer_continue;
+        }
+      }
+      stripptr = NULL;
+    } 
+    *s2 = *s1;
+    s2 += 1;
+_lstrip_outer_continue:
+    s1 += 1;
+  }
+  return stripped;
+}
+
+int rstrip(char *s1, char *s2, char *strip)
+{
+  int stripped = 0;
+  char *stripptr = strip;
+  char *rs1 = s1;
+  if ( s1 == NULL || s2 == NULL || strip == NULL ) {
+    return 0;
+  }
+  rs1 += strlen(s1)-1;
+  while ( rs1 >= s1 ) {
+    for ( stripptr = strip; *stripptr != 0; stripptr += 1) {
+      if ( *rs1 == *stripptr ) {
+        stripped += 1;
+        rs1 -= 1;
+        goto _rstrip_continue;
+      }
+    }
+    break;
+_rstrip_continue:
+    ;
+  }
+  while (s1 <= rs1) {
+    *s2 = *s1;
+    s2 += 1;
+    s1 += 1;
+  }
+  *s2 = 0;
+  return stripped;
+}
+

src/string.h

@@ -8,5 +8,6 @@ int strncat(char *dest, char *src, size_t n);
 void *memset(void *s, char c, size_t n);
 void *memcpy(void *dest, void *src, size_t n);
 int strcmp(char *s1, char *s2);
-
+int lstrip(char *s1, char *s2, char *strip);
+int rstrip(char *s1, char *s2, char *strip);
 #endif /* _STRING_H_ */

tests/basic_parser.c

@@ -0,0 +1,16 @@
+#include "types.h"
+#include "basic.h"
+
+
+int main(void)
+{
+    struct basic_expr *expr;
+    expr = basic_parse_expr("1 + 1");
+    if ( expr == NULL ) return 1;
+    if ( expr->lval_type != BASIC_LVAL_CONST ) return 2;
+    if ( expr->rval_type != BASIC_RVAL_CONST ) return 3;
+    if ( expr->lval.i != 1 ) return 4;
+    if ( expr->rval.i != 1 ) return 5;
+    if ( expr->type != BASIC_OPTP_ADD ) return 6;
+    return 0;
+}

tests/basic_parser.deps

@@ -0,0 +1,5 @@
+basic
+stdlib
+string
+conio
+screen

tests/basic_tokenizer.c

@@ -6,12 +6,12 @@
 char *_tokenize(char *ptr, char *token);
 char *_token_get(void);
 
-#define assert_lvalue(str, lval, ret_null, ret_neq) \
+#define assert_token_value(str, val, ret_null, ret_neq) \
     ptr = _tokenize(str, BASIC_TOKENIZER_TOKENS); \
     value = _token_get(); \
     if ( ptr == NULL ) return ret_null; \
-    rc = strcmp(value, lval); \
-    printf("(value) == (lval) ? : (%s) == (%s) %d\n", value, lval, rc); \
+    rc = strcmp(value, val); \
+    printf("(%s) => (value) == (val) ? : (%s) == (%s) %d\n", str, value, val, rc); \
     if ( rc != 0 ) return ret_neq;
 
 
@@ -21,9 +21,10 @@ int main(void)
     char *value = NULL;
     int rc = 0;
 
-    assert_lvalue("1+1", "1", 1, 2);
-    assert_lvalue("1 + 1", "1", 2, 3);
-    assert_lvalue("10 + 10", "10", 4, 5);
-
+    assert_token_value("1+1", "1", 1, 2);
+    assert_token_value("1 + 1", "1", 2, 3);
+    assert_token_value("10 + 10", "10", 4, 5);
+    assert_token_value("1+ 2", "1", 6, 7)
+    assert_token_value("+ 2", "+", 8, 9)
     return 0;
 }

tests/string_chomp.c

@@ -0,0 +1,19 @@
+#include "string.h"
+#include "stdlib.h"
+#include <stdio.h>
+
+#define assert_strip(method, str, strip, count, rvalue, ret_strcmp, ret_count) \
+    memset((char *)&buff, 0x00, 32); \
+    rc = method(str, (char *)&buff, strip); \
+    printf("method(%s) => (%d, %s)\n", str, rc, (char *)&buff); \
+    if ( rc != count) return ret_count; \
+    if ( strcmp((char *)&buff, rvalue) != 0 ) return ret_strcmp;
+
+int main(void)
+{
+    char buff[32];
+    int rc = 0;
+    assert_strip(lstrip, "   white space", " ", 3, "white space", 1, 2)
+    assert_strip(rstrip, "white space   ", " ", 3, "white space", 3, 4)
+    return 0;
+}

tests/string_chomp.deps

@@ -0,0 +1,2 @@
+string
+stdlib