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kvisc/dos/str/strrev.k
julianb0 18747ae31a
dos
2019-05-30 19:33:22 +02:00

41 lines
609 B
Plaintext

; The OS/K Team licenses this file to you under the MIT license.
; See the LICENSE file in the project root for more information.
;
; void strrev(char *buf, const char *str)
;
strrev:
test b[ax1], b[ax1]
cmovz b[ax0], 0
jz .4
; save str's location
mov rdx, ax1
; go to str's end, just before
; the null terminator
.1:
test b[ax1+1], b[ax1+1]
jz .2
inc ax1
jmp .1
; copy, going backward though str
; and forward through buf
.2:
mov b[ax0], b[ax1]
cmp ax1, rdx
je .3
inc ax0
dec ax1
jmp .2
.3:
mov b[ax0+1], 0
.4:
ret