| 1 | //===-- divmodsi4.S - 32-bit signed integer divide and modulus ------------===// |
|---|
| 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 | // This file implements the __divmodsi4 (32-bit signed integer divide and |
|---|
| 10 | // modulus) function for the ARM architecture. A naive digit-by-digit |
|---|
| 11 | // computation is employed for simplicity. |
|---|
| 12 | // |
|---|
| 13 | //===----------------------------------------------------------------------===// |
|---|
| 14 | |
|---|
| 15 | #include "../assembly.h" |
|---|
| 16 | |
|---|
| 17 | #define ESTABLISH_FRAME \ |
|---|
| 18 | push {r4-r7, lr} ;\ |
|---|
| 19 | add r7, sp, #12 |
|---|
| 20 | #define CLEAR_FRAME_AND_RETURN \ |
|---|
| 21 | pop {r4-r7, pc} |
|---|
| 22 | |
|---|
| 23 | .syntax unified |
|---|
| 24 | .text |
|---|
| 25 | DEFINE_CODE_STATE |
|---|
| 26 | |
|---|
| 27 | @ int __divmodsi4(int divident, int divisor, int *remainder) |
|---|
| 28 | @ Calculate the quotient and remainder of the (signed) division. The return |
|---|
| 29 | @ value is the quotient, the remainder is placed in the variable. |
|---|
| 30 | |
|---|
| 31 | .p2align 3 |
|---|
| 32 | DEFINE_COMPILERRT_FUNCTION(__divmodsi4) |
|---|
| 33 | #if __ARM_ARCH_EXT_IDIV__ |
|---|
| 34 | tst r1, r1 |
|---|
| 35 | beq LOCAL_LABEL(divzero) |
|---|
| 36 | mov r3, r0 |
|---|
| 37 | sdiv r0, r3, r1 |
|---|
| 38 | mls r1, r0, r1, r3 |
|---|
| 39 | str r1, [r2] |
|---|
| 40 | bx lr |
|---|
| 41 | LOCAL_LABEL(divzero): |
|---|
| 42 | mov r0, #0 |
|---|
| 43 | bx lr |
|---|
| 44 | #else |
|---|
| 45 | ESTABLISH_FRAME |
|---|
| 46 | // Set aside the sign of the quotient and modulus, and the address for the |
|---|
| 47 | // modulus. |
|---|
| 48 | eor r4, r0, r1 |
|---|
| 49 | mov r5, r0 |
|---|
| 50 | mov r6, r2 |
|---|
| 51 | // Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31). |
|---|
| 52 | eor ip, r0, r0, asr #31 |
|---|
| 53 | eor lr, r1, r1, asr #31 |
|---|
| 54 | sub r0, ip, r0, asr #31 |
|---|
| 55 | sub r1, lr, r1, asr #31 |
|---|
| 56 | // Unsigned divmod: |
|---|
| 57 | bl SYMBOL_NAME(__udivmodsi4) |
|---|
| 58 | // Apply the sign of quotient and modulus |
|---|
| 59 | ldr r1, [r6] |
|---|
| 60 | eor r0, r0, r4, asr #31 |
|---|
| 61 | eor r1, r1, r5, asr #31 |
|---|
| 62 | sub r0, r0, r4, asr #31 |
|---|
| 63 | sub r1, r1, r5, asr #31 |
|---|
| 64 | str r1, [r6] |
|---|
| 65 | CLEAR_FRAME_AND_RETURN |
|---|
| 66 | #endif |
|---|
| 67 | END_COMPILERRT_FUNCTION(__divmodsi4) |
|---|
| 68 | |
|---|
| 69 | NO_EXEC_STACK_DIRECTIVE |
|---|
| 70 | |
|---|
| 71 | |
|---|
