llvm-project/compiler-rt/lib/arm/modsi3.S

40 lines
1.3 KiB
ArmAsm

/*===-- modsi3.S - 32-bit signed integer modulus --------------------------===//
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
*===----------------------------------------------------------------------===//
*
* This file implements the __modsi3 (32-bit signed integer modulus) function
* for the ARM architecture as a wrapper around the unsigned routine.
*
*===----------------------------------------------------------------------===*/
#include "../assembly.h"
#define ESTABLISH_FRAME \
push {r4, r7, lr} ;\
add r7, sp, #4
#define CLEAR_FRAME_AND_RETURN \
pop {r4, r7, pc}
.syntax unified
.align 3
DEFINE_COMPILERRT_FUNCTION(__modsi3)
ESTABLISH_FRAME
// Set aside the sign of the dividend.
mov r4, r0
// Take absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
eor r2, r0, r0, asr #31
eor r3, r1, r1, asr #31
sub r0, r2, r0, asr #31
sub r1, r3, r1, asr #31
// abs(a) % abs(b)
bl SYMBOL_NAME(__umodsi3)
// Apply sign of dividend to result and return.
eor r0, r0, r4, asr #31
sub r0, r0, r4, asr #31
CLEAR_FRAME_AND_RETURN