Check for underflow (#78)

jbirddog · Jul 8, 2024 · 0c16ba5 · 0c16ba5
1 parent a68c5e0
commit 0c16ba5
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diff --git a/data_stack.inc b/data_stack.inc
@@ -28,12 +28,19 @@ data_stack_push:
 
 data_stack_pop:
 	mov	rsi, [_data_stack.here]
+	cmp	rsi, [_data_stack.base]
+	jle	.underflow
+	
 	std
 	lodsq
 	mov	[_data_stack.here], rsi
 	lodsq
 	cld
+	
 	ret
+	
+	.underflow:
+	die	ERR_UNDERFLOW
 
 data_stack_depth:
 	mov	rax, [_data_stack.here]

diff --git a/defs.inc b/defs.inc
@@ -11,6 +11,7 @@ ERR_BAD_BASE	= 167
 ERR_BAD_PAD	= 168
 ERR_NO_WORD	= 169
 ERR_BAD_SE	= 170
+ERR_UNDERFLOW	= 171
 
 TYPE_OFFSET	= 0x00