forked from mirrors/linux
2874c5fd28
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
55 lines
1.7 KiB
ArmAsm
55 lines
1.7 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Divide a 64-bit unsigned number by a 32-bit unsigned number.
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* This routine assumes that the top 32 bits of the dividend are
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* non-zero to start with.
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* On entry, r3 points to the dividend, which get overwritten with
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* the 64-bit quotient, and r4 contains the divisor.
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* On exit, r3 contains the remainder.
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*
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* Copyright (C) 2002 Paul Mackerras, IBM Corp.
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*/
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#include <asm/ppc_asm.h>
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#include <asm/processor.h>
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_GLOBAL(__div64_32)
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lwz r5,0(r3) # get the dividend into r5/r6
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lwz r6,4(r3)
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cmplw r5,r4
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li r7,0
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li r8,0
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blt 1f
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divwu r7,r5,r4 # if dividend.hi >= divisor,
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mullw r0,r7,r4 # quotient.hi = dividend.hi / divisor
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subf. r5,r0,r5 # dividend.hi %= divisor
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beq 3f
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1: mr r11,r5 # here dividend.hi != 0
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andis. r0,r5,0xc000
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bne 2f
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cntlzw r0,r5 # we are shifting the dividend right
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li r10,-1 # to make it < 2^32, and shifting
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srw r10,r10,r0 # the divisor right the same amount,
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addc r9,r4,r10 # rounding up (so the estimate cannot
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andc r11,r6,r10 # ever be too large, only too small)
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andc r9,r9,r10
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addze r9,r9
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or r11,r5,r11
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rotlw r9,r9,r0
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rotlw r11,r11,r0
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divwu r11,r11,r9 # then we divide the shifted quantities
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2: mullw r10,r11,r4 # to get an estimate of the quotient,
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mulhwu r9,r11,r4 # multiply the estimate by the divisor,
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subfc r6,r10,r6 # take the product from the divisor,
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add r8,r8,r11 # and add the estimate to the accumulated
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subfe. r5,r9,r5 # quotient
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bne 1b
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3: cmplw r6,r4
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blt 4f
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divwu r0,r6,r4 # perform the remaining 32-bit division
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mullw r10,r0,r4 # and get the remainder
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add r8,r8,r0
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subf r6,r10,r6
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4: stw r7,0(r3) # return the quotient in *r3
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stw r8,4(r3)
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mr r3,r6 # return the remainder in r3
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blr
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