all repos — xyw @ c96add80119b624d5377eafe543c88140559f7af

A minimal virtual machine and assembler for terminals.

Fixed a few bugs related to bounds checking and similar.
h3rald h3rald@h3rald.com
Fri, 13 Feb 2026 07:37:58 +0100
commit

c96add80119b624d5377eafe543c88140559f7af

parent

cf74ea2e46cd7f9ef5d2bdb1a06d2cfb0dd0b95d

3 files changed, 9 insertions(+), 8 deletions(-)

jump to
M xyw.c → xyw.c 
@@ -33,7 +33,7 @@ int main(int argc, char *argv[])
 {
     xyw_argc = argc;
 
-    for (int i = 1; i < argc; i++)
+    for (int i = 1; i < argc && i < 32; i++)
     {
         xyw_argv[i] = argv[i];
         if (flag(argv[i], "debug"))

@@ -79,4 +79,5 @@ }
             break;
         }
     }
+    return 0;
 }
M xywasm.c → xywasm.c 
@@ -74,7 +74,7 @@ // Tracks whether we are inside a directive or not
 static unsigned int directive = 0;
 
 // Bytecode to be written
-xyw_byte data[0xffff] = {};
+xyw_byte data[0x10000] = {};
 
 // Current write pointer
 xyw_word ptr = 0;

@@ -708,9 +708,8 @@ }
             }
             break;
         }
-        if (length > DIRECTIVE_CONTENT_MAX_LENGTH)
+        if (length >= DIRECTIVE_CONTENT_MAX_LENGTH - 1)
         {
-
             token_error("Macro contents too long");
             return -1;
         }

@@ -872,7 +871,7 @@ token_column = ctx->column;
                 token_started = 1;
             }
             ctx->column++;
-            if (token_length > TOKEN_MAX_LENGTH)
+            if (token_length >= TOKEN_MAX_LENGTH - 1)
             {
                 token_error("Token too long");
                 return TOKEN_END_INVALID;

@@ -938,7 +937,7 @@ return TOKEN_END_INVALID;
                 }
             }
             ctx->column++;
-            if (token_length > TOKEN_MAX_LENGTH)
+            if (token_length >= TOKEN_MAX_LENGTH - 1)
             {
                 token_error("Token too long");
                 return TOKEN_END_INVALID;

@@ -987,7 +986,7 @@ token_column = ctx->column;
                 token_started = 1;
             }
             ctx->column++;
-            if (token_length > TOKEN_MAX_LENGTH)
+            if (token_length >= TOKEN_MAX_LENGTH - 1)
             {
                 token_error("Token too long");
                 return TOKEN_END_INVALID;
M xywrun.c → xywrun.c 
@@ -8,7 +8,7 @@ #include "devices/clock.h"
 #include "devices/file.h"
 #include "devices/beeper.h"
 
-#define MEMORY_SIZE 0xffff
+#define MEMORY_SIZE 0x10000
 #define STACK_SIZE 0xff
 
 #define USER_MEMORY_START 0x000

@@ -89,6 +89,7 @@ 
 //// Helpers to retrieve device number and address within the device
 static inline int get_device(xyw_word addr)
 {
+    if (addr < DEVICE_AREA_START) return -1;
     return (addr - DEVICE_AREA_START) / 16;
 }