Fix strcmp()

string.asm

@@ -96,32 +96,33 @@ strcat:
 	leave
 	ret
 ;----- strcmp(char* str1, char* str2) -----;
-; return value: 0 if both strings are the same, otherwise index in array str1 where strings are to become different
+; return value: 0 if both strings are the same, otherwise index in array str1 where strings mismatch
 ; returns -1 if str2 is longer than str1 and no difference was found before that happens
-; TODO: FIX length 13 for TEST strcmp(strBuff1, str1) (see tests.asm, strcmp test 1)
 strcmp:
 	push	rbp
 	mov	rbp, rsp
 
 	call	strlen
-	mov	rcx, rax
-	mov	rax, -1
+	xor	r10, r10
 	.compareLoop:
-		inc	rax
-		cmp	byte [rdi+rax], 0x0
-		je	.eosFound
-		mov	r10b, byte [rsi+rax]
-		cmp	byte [rdi+rax], r10b
-		je	.compareLoop
-	jmp	.quit
+		cmp	byte [rdi], 0x0
+		je	.0f
+		mov	r11b, byte [rsi]
+		cmp	byte [rdi], r11b
+		jne	.mismatch
+		inc	rdi
+		inc	rsi
+		inc	r10
+		jmp	.compareLoop
+	.0f:
+		mov	rax, -1
+		cmp	byte [rsi], 0x0
+		jne	.quit
+		xor	rax, rax
+		jmp	.quit
 
-	.eosFound:
-	mov	r10, rax
-	mov	rdi, rsi
-	call	strlen
-	cmp	rax, r10
-	jle	.quit
-	mov	rax, -1
+	.mismatch:
+		mov	rax, r10
 
 	.quit:
 	leave