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/*===-- udivsi3.S - 32-bit unsigned integer divide ------------------------===//
*
* 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 __udivsi3 (32-bit unsigned integer divide)
* function for the ARM 32-bit architecture.
*
*===----------------------------------------------------------------------===*/
#include "../assembly.h"
.syntax unified
.text
#if __ARM_ARCH_ISA_THUMB == 2
.thumb
#endif
.p2align 2
DEFINE_AEABI_FUNCTION_ALIAS(__aeabi_uidiv, __udivsi3)
@ unsigned int __udivsi3(unsigned int divident, unsigned int divisor)
@ Calculate and return the quotient of the (unsigned) division.
#if __ARM_ARCH_ISA_THUMB == 2
DEFINE_COMPILERRT_THUMB_FUNCTION(__udivsi3)
#else
DEFINE_COMPILERRT_FUNCTION(__udivsi3)
#endif
#if __ARM_ARCH_EXT_IDIV__
tst r1, r1
beq LOCAL_LABEL(divby0)
udiv r0, r0, r1
bx lr
#else
cmp r1, #1
bcc LOCAL_LABEL(divby0)
IT(eq)
JMPc(lr, eq)
cmp r0, r1
ITT(cc)
movcc r0, #0
JMPc(lr, cc)
/*
* Implement division using binary long division algorithm.
*
* r0 is the numerator, r1 the denominator.
*
* The code before JMP computes the correct shift I, so that
* r0 and (r1 << I) have the highest bit set in the same position.
* At the time of JMP, ip := .Ldiv0block - 12 * I.
* This depends on the fixed instruction size of block.
* For ARM mode, this is 12 Bytes, for THUMB mode 14 Bytes.
*
* block(shift) implements the test-and-update-quotient core.
* It assumes (r0 << shift) can be computed without overflow and
* that (r0 << shift) < 2 * r1. The quotient is stored in r3.
*/
# ifdef __ARM_FEATURE_CLZ
clz ip, r0
clz r3, r1
/* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */
sub r3, r3, ip
# if __ARM_ARCH_ISA_THUMB == 2
adr ip, LOCAL_LABEL(div0block) + 1
sub ip, ip, r3, lsl #1
# else
adr ip, LOCAL_LABEL(div0block)
# endif
sub ip, ip, r3, lsl #2
sub ip, ip, r3, lsl #3
mov r3, #0
bx ip
# else
# if __ARM_ARCH_ISA_THUMB == 2
# error THUMB mode requires CLZ or UDIV
# endif
mov r2, r0
adr ip, LOCAL_LABEL(div0block)
lsr r3, r2, #16
cmp r3, r1
movhs r2, r3
subhs ip, ip, #(16 * 12)
lsr r3, r2, #8
cmp r3, r1
movhs r2, r3
subhs ip, ip, #(8 * 12)
lsr r3, r2, #4
cmp r3, r1
movhs r2, r3
subhs ip, #(4 * 12)
lsr r3, r2, #2
cmp r3, r1
movhs r2, r3
subhs ip, ip, #(2 * 12)
/* Last block, no need to update r2 or r3. */
cmp r1, r2, lsr #1
subls ip, ip, #(1 * 12)
mov r3, #0
JMP(ip)
# endif
#define IMM #
#define block(shift) \
cmp r0, r1, lsl IMM shift; \
ITT(hs); \
WIDE(addhs) r3, r3, IMM (1 << shift); \
WIDE(subhs) r0, r0, r1, lsl IMM shift
block(31)
block(30)
block(29)
block(28)
block(27)
block(26)
block(25)
block(24)
block(23)
block(22)
block(21)
block(20)
block(19)
block(18)
block(17)
block(16)
block(15)
block(14)
block(13)
block(12)
block(11)
block(10)
block(9)
block(8)
block(7)
block(6)
block(5)
block(4)
block(3)
block(2)
block(1)
LOCAL_LABEL(div0block):
block(0)
mov r0, r3
JMP(lr)
#endif /* __ARM_ARCH_EXT_IDIV__ */
LOCAL_LABEL(divby0):
mov r0, #0
#ifdef __ARM_EABI__
b __aeabi_idiv0
#else
JMP(lr)
#endif
END_COMPILERRT_FUNCTION(__udivsi3)
|
