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//===-------- modsi3.S - Implement modsi3 ---------------------------------===//
//
// 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.
//
//===----------------------------------------------------------------------===//
#include "../assembly.h"
//
// extern int32_t __modsi3(int32_t a, int32_t b);
//
// Returns the remainder when dividing two 32-bit signed integers.
// Conceptually, the function is: { return a - (a / b) * b; }
// But if you write that in C, llvm compiles it to a call to __modsi3...
//
.align 2
DEFINE_COMPILERRT_FUNCTION(__modsi3)
push {r4, r5, r7, lr}
add r7, sp, #8 // set stack frame
mov r5, r0 // save a
mov r4, r1 // save b
bl ___divsi3 // compute a/b
#if __ARM_ARCH_7A__
mls r0, r4, r0, r5 // mulitple result * b and subtract from a
#else
// before armv7, does not have "mls" instruction
mul r3, r0, r4 // multiple result * b
sub r0, r5, r3 // a - result
#endif
pop {r4, r5, r7, pc}
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