source: trunk/libs/newlib/src/newlib/libc/machine/rx/strncpy.S @ 444

        .file   "strncpy.S"

        .section .text
        .global  _strncpy
        .type    _strncpy,@function
_strncpy:
#ifdef __RX_DISALLOW_STRING_INSNS__
        cmp     #0, r3
        beq     3f
        
        mov     r1, r4          ; Preserve R1 for the return value.

2:      mov.b   [r2+], r5       ; Copy bytes until...
        mov.b   r5, [r4+]
        sub     #1, r3
        beq     3f              ; ... our count reaches zero
        cmp     #0, r5
        bne     2b              ; ... or we have written a NUL byte

4:      mov.b   r5, [r4+]       ; Continue to write further NUL bytes
        sub     #1, r3
        bne     4b              ; until the count reaches zero.

3:      rts
        
#else
        mov     r1, r4          ; Save a copy of the dest pointer.
        mov     r3, r5          ; Save a copy of the byte count
        smovu                   ; Copy the bytes
        cmp     #0, r3          ; If we have copied the number of bytes requested
        beq     1f              ;  then skip the next bit:
        add     r4, r5, r1      ; Point to the last byte that we are supposed to write.
        sub     r3, r1          ; Subtract the number of bytes left to be written.
        mov     #0, r2          ; Fill the remaining bytes with NULs,
        sstr.b
1:
        mov     r4, r1          ; Return the destination pointer
        rts
#endif
        .size _strncpy, . - _strncpy