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      1 /*===-- modsi3.S - 32-bit signed integer modulus --------------------------===//
      2  *
      3  *                     The LLVM Compiler Infrastructure
      4  *
      5  * This file is dual licensed under the MIT and the University of Illinois Open
      6  * Source Licenses. See LICENSE.TXT for details.
      7  *
      8  *===----------------------------------------------------------------------===//
      9  *
     10  * This file implements the __modsi3 (32-bit signed integer modulus) function
     11  * for the ARM architecture as a wrapper around the unsigned routine.
     12  *
     13  *===----------------------------------------------------------------------===*/
     14 
     15 #include "../assembly.h"
     16 
     17 #define ESTABLISH_FRAME \
     18     push   {r4, lr}
     19 #define CLEAR_FRAME_AND_RETURN \
     20     pop    {r4, pc}
     21 
     22 	.syntax unified
     23 	.text
     24 #if __ARM_ARCH_ISA_THUMB == 2
     25 	.thumb
     26 #endif
     27 
     28 @ int __modsi3(int divident, int divisor)
     29 @   Calculate and return the remainder of the (signed) division.
     30 
     31 	.p2align 3
     32 #if __ARM_ARCH_ISA_THUMB == 2
     33 DEFINE_COMPILERRT_THUMB_FUNCTION(__modsi3)
     34 #else
     35 DEFINE_COMPILERRT_FUNCTION(__modsi3)
     36 #endif
     37 #if __ARM_ARCH_EXT_IDIV__
     38 	tst     r1, r1
     39 	beq     LOCAL_LABEL(divzero)
     40 	sdiv	r2, r0, r1
     41 	mls 	r0, r2, r1, r0
     42 	bx      lr
     43 LOCAL_LABEL(divzero):
     44 	mov     r0, #0
     45 	bx      lr
     46 #else
     47     ESTABLISH_FRAME
     48     //  Set aside the sign of the dividend.
     49     mov     r4,     r0
     50     //  Take absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
     51     eor     r2,     r0, r0, asr #31
     52     eor     r3,     r1, r1, asr #31
     53     sub     r0,     r2, r0, asr #31
     54     sub     r1,     r3, r1, asr #31
     55     //  abs(a) % abs(b)
     56     bl     SYMBOL_NAME(__umodsi3)
     57     //  Apply sign of dividend to result and return.
     58     eor     r0,     r0, r4, asr #31
     59     sub     r0,     r0, r4, asr #31
     60     CLEAR_FRAME_AND_RETURN
     61 #endif
     62 END_COMPILERRT_FUNCTION(__modsi3)
     63