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      1 /*===-- divmodsi4.S - 32-bit signed integer divide and 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 __divmodsi4 (32-bit signed integer divide and
     11  * modulus) function for the ARM architecture.  A naive digit-by-digit
     12  * computation is employed for simplicity.
     13  *
     14  *===----------------------------------------------------------------------===*/
     15 
     16 #include "../assembly.h"
     17 
     18 #define ESTABLISH_FRAME    \
     19     push   {r4-r6, lr}
     20 #define CLEAR_FRAME_AND_RETURN \
     21     pop    {r4-r6, pc}
     22 
     23 	.syntax unified
     24 	.text
     25 #if __ARM_ARCH_ISA_THUMB == 2
     26 	.thumb
     27 #endif
     28 
     29 @ int __divmodsi4(int divident, int divisor, int *remainder)
     30 @   Calculate the quotient and remainder of the (signed) division.  The return
     31 @   value is the quotient, the remainder is placed in the variable.
     32 
     33 	.p2align 3
     34 #if __ARM_ARCH_ISA_THUMB == 2
     35 DEFINE_COMPILERRT_THUMB_FUNCTION(__divmodsi4)
     36 #else
     37 DEFINE_COMPILERRT_FUNCTION(__divmodsi4)
     38 #endif
     39 #if __ARM_ARCH_EXT_IDIV__
     40 	tst     r1, r1
     41 	beq     LOCAL_LABEL(divzero)
     42 	mov 	r3, r0
     43 	sdiv	r0, r3, r1
     44 	mls 	r1, r0, r1, r3
     45 	str 	r1, [r2]
     46 	bx  	lr
     47 LOCAL_LABEL(divzero):
     48 	mov     r0, #0
     49 	bx      lr
     50 #else
     51     ESTABLISH_FRAME
     52 //  Set aside the sign of the quotient and modulus, and the address for the
     53 //  modulus.
     54     eor     r4,     r0, r1
     55     mov     r5,     r0
     56     mov     r6,     r2
     57 //  Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
     58     eor     ip,     r0, r0, asr #31
     59     eor     lr,     r1, r1, asr #31
     60     sub     r0,     ip, r0, asr #31
     61     sub     r1,     lr, r1, asr #31
     62 //  Unsigned divmod:
     63     bl      SYMBOL_NAME(__udivmodsi4)
     64 //  Apply the sign of quotient and modulus
     65     ldr     r1,    [r6]
     66     eor     r0,     r0, r4, asr #31
     67     eor     r1,     r1, r5, asr #31
     68     sub     r0,     r0, r4, asr #31
     69     sub     r1,     r1, r5, asr #31
     70     str     r1,    [r6]
     71     CLEAR_FRAME_AND_RETURN
     72 #endif
     73 END_COMPILERRT_FUNCTION(__divmodsi4)
     74