optimize str(r)str

Author: ZERICO2005

src/libc/strrstr.src

@@ -17,17 +17,16 @@ _strrstr:
 	ld	bc, 0
 	cpir
 	sbc	hl, hl
-	dec	hl
-	sbc	hl, bc		; carry will be cleared
+	scf
+	sbc	hl, bc		; carry will be set
 	ex	(sp), hl	; strlen(needle)
 	push	hl		; needle
 
 	ex	de, hl
 	push	hl
-	ld	bc, 0
+	ld	bc, -1
 	cpir
 	sbc	hl, hl
-	dec	hl
 	sbc	hl, bc
 	ex	(sp), hl	; strlen(haystack)
 	push	hl		; haystack

src/libc/strstr.src

@@ -24,17 +24,16 @@ _strstr:
 	ld	bc, 0
 	cpir
 	sbc	hl, hl
-	dec	hl
-	sbc	hl, bc		; carry will be cleared
+	scf
+	sbc	hl, bc		; carry will be set
 	ex	(sp), hl	; strlen(needle)
 	push	hl		; needle
 
 	ex	de, hl
 	push	hl
-	ld	bc, 0
+	ld	bc, -1
 	cpir
 	sbc	hl, hl
-	dec	hl
 	sbc	hl, bc
 	ex	(sp), hl	; strlen(haystack)
 	push	hl		; haystack