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/*===-- divmodsi4.S - 32-bit signed integer divide and 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 __divmodsi4 (32-bit signed integer divide and
* modulus) function for the ARM architecture. A naive digit-by-digit
* computation is employed for simplicity.
*
*===----------------------------------------------------------------------===*/
#include "../assembly.h"
#define ESTABLISH_FRAME \
push {r4-r7, lr} ;\
add r7, sp, #12
#define CLEAR_FRAME_AND_RETURN \
pop {r4-r7, pc}
.syntax unified
.text
#if __ARM_ARCH_ISA_THUMB == 2
.thumb
#endif
@ int __divmodsi4(int divident, int divisor, int *remainder)
@ Calculate the quotient and remainder of the (signed) division. The return
@ value is the quotient, the remainder is placed in the variable.
.p2align 3
#if __ARM_ARCH_ISA_THUMB == 2
DEFINE_COMPILERRT_THUMB_FUNCTION(__divmodsi4)
#else
DEFINE_COMPILERRT_FUNCTION(__divmodsi4)
#endif
#if __ARM_ARCH_EXT_IDIV__
tst r1, r1
beq LOCAL_LABEL(divzero)
mov r3, r0
sdiv r0, r3, r1
mls r1, r0, r1, r3
str r1, [r2]
bx lr
LOCAL_LABEL(divzero):
mov r0, #0
bx lr
#else
ESTABLISH_FRAME
// Set aside the sign of the quotient and modulus, and the address for the
// modulus.
eor r4, r0, r1
mov r5, r0
mov r6, r2
// Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
eor ip, r0, r0, asr #31
eor lr, r1, r1, asr #31
sub r0, ip, r0, asr #31
sub r1, lr, r1, asr #31
// Unsigned divmod:
bl SYMBOL_NAME(__udivmodsi4)
// Apply the sign of quotient and modulus
ldr r1, [r6]
eor r0, r0, r4, asr #31
eor r1, r1, r5, asr #31
sub r0, r0, r4, asr #31
sub r1, r1, r5, asr #31
str r1, [r6]
CLEAR_FRAME_AND_RETURN
#endif
END_COMPILERRT_FUNCTION(__divmodsi4)
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