make strncmp direction safe

[rrq/rrqforth.git] / wordlists.asm

diff --git a/wordlists.asm b/wordlists.asm
index 0ee7aecedb83c134e75a86d0f82f30661015a27b..1604168c5bb754c7f6122cfb1bcacc9ffa6b8692 100644 (file)
--- a/wordlists.asm
+++ b/wordlists.asm
@@ -88,12 +88,20 @@ p_strlen_LOOP:
        pop rsi
        cmp rcx,0
        jle p_strncpy_END
-       cld
+       cmp rdi,rsi
+       je p_strncpy_END
+       jl p_strncpy_LOOP
+       ;; copy down
+       std ; Direction is decrementing
+       add rdi,rcx
+       dec rdi
+       add rsi,rcx
+       dec rsi
 p_strncpy_LOOP:
+       rep
        movsb
-       dec rcx
-       jg p_strncpy_LOOP
 p_strncpy_END:
+       cld ; Restore default direction as incrementing
        popr rsi
        next