Optimization

git-svn-id: svn://svn.cc65.org/cc65/trunk@2151 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/common/memchr.s b/libsrc/common/memchr.s
index 59186ae453aeec31d289d3dc1d9a239d5edc679b..c4556370f576534ad103744e56e01192dbf23b02 100644 (file)
--- a/libsrc/common/memchr.s
+++ b/libsrc/common/memchr.s
@@ -1,57 +1,57 @@
 ;
-; Ullrich von Bassewitz, 09.06.1998
+; Ullrich von Bassewitz, 2003-05-05
 ;
-; void* memchr (const void* p, int c, size_t n);
+; void* __fastcall__ memchr (const void* p, int c, size_t n);
 ;
 
-       .export         _memchr
-       .import         popax, return0
-       .importzp       ptr1, ptr2, tmp1
+       .export         _memchr
+       .import         popax, return0
+       .importzp       ptr1, ptr2
 
 
-_memchr:
-               sta     ptr2            ; Save n
-       stx     ptr2+1
-       jsr     popax           ; get c
-       sta     tmp1
+.proc   _memchr
+
+        eor     #$FF
+               sta     ptr2
+        txa
+        eor     #$FF
+       sta     ptr2+1          ; Save ones complement of n
+       jsr     popax           ; get c
+       pha
                jsr     popax           ; get p
                sta     ptr1
                stx     ptr1+1
 
-               ldy     #0
-       lda     tmp1            ; get c
-       ldx     ptr2            ; use X as low counter byte
-       beq     L3              ; check high byte
+        ldy     #$00
+        pla                     ; Get c
+        ldx     ptr2            ; Use X as low counter byte
 
-; Search for the char
+L1:     inx
+        beq     L3
+L2:     cmp     (ptr1),y
+        beq     found
+        iny
+        bne     L1
+        inc     ptr1+1
+        bne     L1              ; Branch always
 
-L1:    cmp     (ptr1),y
-               beq     L5              ; jump if found
-       iny
-       bne     L2
-       inc     ptr1+1
-L2:    cpx     #0
-       beq     L3
-       dex
-       jmp     L1
-L3:    ldx     ptr2+1          ; Check high byte
-       beq     L4              ; Jump if counter off
-       dec     ptr2+1
-       ldx     #$FF
-       bne     L1              ; branch always
+L3:     inc     ptr2+1          ; Bump counter high byte
+        bne     L2
 
-; Character not found, return zero
+; Not found, return NULL
 
-L4:    jmp     return0
+notfound:
+        jmp     return0
 
-; Character found, calculate pointer
+; Found, return pointer to char
 
-L5:    ldx     ptr1+1          ; get high byte of pointer
+found:  ldx    ptr1+1          ; get high byte of pointer
                tya                     ; low byte offset
                clc
                adc     ptr1
-               bcc     L6
+               bcc     L9
                inx
-L6:    rts
+L9:    rts
 
+.endproc