Use more compact loops.

2020-11-01 22:59:07 +01:00
parent 99c0815cdb
commit f59cb9af06
13 changed files with 90 additions and 94 deletions
--- a/libsrc/common/strncat.s
+++ b/libsrc/common/strncat.s
@@ -5,17 +5,17 @@
 ; char* strncat (char* dest, const char* src, size_t n);
 ;

-        .export         _strncat
-        .import         popax, popptr1
-        .importzp       ptr1, ptr2, ptr3, tmp1, tmp2
-        .macpack        cpu
+.export         _strncat
+.import         popax, popptr1
+.importzp       ptr1, ptr2, ptr3, tmp1, tmp2
+.macpack        cpu
        
 _strncat:
-    eor #$FF        ; one's complement to count upwards
-    sta tmp1
-    txa
-    eor #$FF
-    sta tmp2
+    inx
+    stx tmp2
+    tax
+    inx
+    stx tmp1        ; save count with each byte incremented separately
    
    jsr popptr1     ; get src

@@ -49,9 +49,9 @@ L2: sty ptr2
 L3: ldy #0
    ldx tmp1        ; low counter byte

-L4: inx
+L4: dex
    bne L5
-    inc tmp2
+    dec tmp2
    beq L6          ; jump if done
 L5: lda (ptr1),y
    sta (ptr2),y