| 1 | //===------------ udivmodqi4.S - uint8 div & mod --------------------------===// |
|---|
| 2 | // |
|---|
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
|---|
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
|---|
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
|---|
| 6 | // |
|---|
| 7 | //===----------------------------------------------------------------------===// |
|---|
| 8 | // |
|---|
| 9 | // As described at |
|---|
| 10 | // https://gcc.gnu.org/wiki/avr-gcc#Exceptions_to_the_Calling_Convention, the |
|---|
| 11 | // prototype is `struct {uint8, uint8} __udivmodqi4(uint8, uint8)`. |
|---|
| 12 | // The uint8 quotient is returned via R24, and the uint8 remainder is returned |
|---|
| 13 | // via R25, while R23 is clobbered. |
|---|
| 14 | // |
|---|
| 15 | //===----------------------------------------------------------------------===// |
|---|
| 16 | |
|---|
| 17 | .text |
|---|
| 18 | .align 2 |
|---|
| 19 | |
|---|
| 20 | .globl __udivmodqi4 |
|---|
| 21 | .type __udivmodqi4, @function |
|---|
| 22 | |
|---|
| 23 | __udivmodqi4: |
|---|
| 24 | sub r25, r25 ; Initialize the remainder to zero. |
|---|
| 25 | ldi r23, 9 ; Only loop 8 rounds for uint8. |
|---|
| 26 | |
|---|
| 27 | __udivmodqi4_loop: |
|---|
| 28 | adc r24, r24 |
|---|
| 29 | dec r23 |
|---|
| 30 | breq __udivmodqi4_end |
|---|
| 31 | adc r25, r25 |
|---|
| 32 | cp r25, r22 ; Compare with the divisor. |
|---|
| 33 | brcs __udivmodqi4_loop |
|---|
| 34 | sub r25, r22 ; Subtract the divisor. |
|---|
| 35 | rjmp __udivmodqi4_loop |
|---|
| 36 | |
|---|
| 37 | __udivmodqi4_end: |
|---|
| 38 | com r24 ; The uint8 quotient is returned via R24. |
|---|
| 39 | ret ; The uint8 remainder is returned via R25. |
|---|
| 40 | |
|---|
