X-Git-Url: http://git.subgeniuskitty.com/vvhitespace/.git/blobdiff_plain/8d17aa4158cb8dade01d69aa015a1b3fb159995d..4fba07dca7fb9275b51e5095a774fe69eeab4660:/vv_interpreter.c

diff --git a/vv_interpreter.c b/vv_interpreter.c
index 1d5d906..b548a50 100644
--- a/vv_interpreter.c
+++ b/vv_interpreter.c
@@ -126,7 +126,10 @@ parse_label(uint8_t * code, size_t * pc)
 uint16_t
 check_label(size_t * labels, uint16_t label, size_t * pc)
 {
-    if(!labels[label]) ws_die(pc, "uninitialized label (forgot an include?)");
+    if (!labels[label]) {
+        fprintf(stderr, "Trying to process label 0x%X.\n", label);
+        ws_die(pc, "uninitialized label (forgot an include?)");
+    }
     return label;
 }
 
@@ -159,14 +162,26 @@ process_imp_stack(uint8_t * code, size_t * pc, int64_t ** sp)
 
                 /* Now, construct the number and push to TOS. */
                 /* I'm assuming the numbers are read MSb first. */
-                int64_t number = 0;
+                uint64_t number = 0; /* Unsigned to accomodate magnitude of most negative number. */
                 uint8_t temp;
                 while ((temp = next_code_byte(code,pc)) != '\n') {
                     if (temp == '\v') ws_die(pc, "non-binary digit in number");
                     number <<= 1;
                     if (temp == '\t') number++;
                 }
-                stack_push(sp, number*sign);
+                /* Without temporarily casting to something >64-bit, the most negative */
+                /* number will overflow when performing 'number*sign'. Instead, we     */
+                /* pick off the most negative number as a special case.                */
+                if (number == (1ULL << 63) && sign == -1) {
+                    /* C parses negative integer literals first as signed positive */
+                    /* integer literals, then applying a unary negation operator.  */
+                    /* Thus, the most negative value is unreachable directly.      */
+                    int64_t number_temp = -9223372036854775807LL; /* First store -((2^63)-1)  */
+                    number_temp--;                                /* Now turn it into -(2^63) */
+                    stack_push(sp, number_temp);
+                } else {
+                    stack_push(sp, number*sign);
+                }
             }
             break;
         case '\n':
@@ -238,7 +253,7 @@ process_imp_arithmetic(uint8_t * code, size_t * pc, int64_t ** sp)
                     case '\t':
                         /* Modulo */
                         temp = stack_pop(sp);
-                        stack_push(sp, stack_pop(sp)%temp);
+                        stack_push(sp, llabs(stack_pop(sp) % llabs(temp)));
                         break;
                     default: ws_die(pc, "malformed arithmetic IMP"); break;
                 }