; 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
    ; xxx why is dec'ing needed?
    lea rdx, b[ax1 + -1]

    ; 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