| .file "strncat.S" |
| |
| .section .text |
| .global _strncat |
| .type _strncat,@function |
| _strncat: |
| ;; On entry: r1 => Destination |
| ;; r2 => Source |
| ;; r3 => Max number of bytes to copy |
| |
| mov r1, r4 ; Save a copy of the dest pointer. |
| mov r2, r5 ; Save a copy of the source pointer. |
| mov r3, r14 ; Save a copy of the byte count. |
| |
| mov #0, r2 ; Search for the NUL byte. |
| mov #-1, r3 ; Search until we run out of memory. |
| suntil.b ; Find the end of the destination string. |
| sub #1, r1 ; suntil.b leaves r1 pointing to the byte beyond the NUL. |
| |
| mov r14, r3 ; Restore the limit on the number of bytes copied. |
| mov r5, r2 ; Restore the source pointer. |
| mov r1, r5 ; Save a copy of the dest pointer. |
| smovu ; Copy source to destination. |
| |
| add #0, r14, r3 ; Restore the number of bytes to copy (again), but this time set the Z flag as well. |
| beq 1f ; If we copied 0 bytes then we already know that the dest string is NUL terminated, so we do not have to do anything. |
| mov #0, r2 ; Otherwise we must check to see if a NUL byte |
| mov r5, r1 ; was included in the bytes that were copied. |
| suntil.b |
| beq 1f ; Z flag is set if a match was found. |
| add r14, r5 ; Point at byte after end of copied bytes. |
| mov.b #0, [r5] ; Store a NUL there. |
| 1: |
| mov r4, r1 ; Return the original dest pointer. |
| rts |