Optimize stpcpy's size and speed

2024-09-04 22:52:52 +02:00
parent 5e5dd1d6c4
commit 55d3a6ea39
4 changed files with 38 additions and 11 deletions
--- a/libsrc/common/stpcpy.s
+++ b/libsrc/common/stpcpy.s
@@ -0,0 +1,22 @@
+;
+; Colin Leroy-Mira, 4 Sept. 2024
+;
+; char* stpcpy (char* dest, const char* src);
+;
+
+        .export         _stpcpy
+        .import         _strcpy
+
+        .importzp       tmp1, ptr2
+
+_stpcpy:
+        jsr     _strcpy
+
+        ldx     ptr2+1        ; Load dest pointer's last high byte
+        tya                   ; Get the last offset strcpy wrote to
+
+        clc
+        adc     ptr2          ; Add to low byte value
+        bcc     :+
+        inx
+:       rts                   ; Return pointer to dest's terminator