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| /* SPDX-License-Identifier: GPL-2.0-or-later */
| /*
| * Divide a 64-bit unsigned number by a 32-bit unsigned number.
| * This routine assumes that the top 32 bits of the dividend are
| * non-zero to start with.
| * On entry, r3 points to the dividend, which get overwritten with
| * the 64-bit quotient, and r4 contains the divisor.
| * On exit, r3 contains the remainder.
| *
| * Copyright (C) 2002 Paul Mackerras, IBM Corp.
| */
| #include "ppc_asm.h"
|
| .globl __div64_32
| __div64_32:
| lwz r5,0(r3) # get the dividend into r5/r6
| lwz r6,4(r3)
| cmplw r5,r4
| li r7,0
| li r8,0
| blt 1f
| divwu r7,r5,r4 # if dividend.hi >= divisor,
| mullw r0,r7,r4 # quotient.hi = dividend.hi / divisor
| subf. r5,r0,r5 # dividend.hi %= divisor
| beq 3f
| 1: mr r11,r5 # here dividend.hi != 0
| andis. r0,r5,0xc000
| bne 2f
| cntlzw r0,r5 # we are shifting the dividend right
| li r10,-1 # to make it < 2^32, and shifting
| srw r10,r10,r0 # the divisor right the same amount,
| addc r9,r4,r10 # rounding up (so the estimate cannot
| andc r11,r6,r10 # ever be too large, only too small)
| andc r9,r9,r10
| addze r9,r9
| or r11,r5,r11
| rotlw r9,r9,r0
| rotlw r11,r11,r0
| divwu r11,r11,r9 # then we divide the shifted quantities
| 2: mullw r10,r11,r4 # to get an estimate of the quotient,
| mulhwu r9,r11,r4 # multiply the estimate by the divisor,
| subfc r6,r10,r6 # take the product from the divisor,
| add r8,r8,r11 # and add the estimate to the accumulated
| subfe. r5,r9,r5 # quotient
| bne 1b
| 3: cmplw r6,r4
| blt 4f
| divwu r0,r6,r4 # perform the remaining 32-bit division
| mullw r10,r0,r4 # and get the remainder
| add r8,r8,r0
| subf r6,r10,r6
| 4: stw r7,0(r3) # return the quotient in *r3
| stw r8,4(r3)
| mr r3,r6 # return the remainder in r3
| blr
|
| /*
| * Extended precision shifts.
| *
| * Updated to be valid for shift counts from 0 to 63 inclusive.
| * -- Gabriel
| *
| * R3/R4 has 64 bit value
| * R5 has shift count
| * result in R3/R4
| *
| * ashrdi3: arithmetic right shift (sign propagation)
| * lshrdi3: logical right shift
| * ashldi3: left shift
| */
| .globl __ashrdi3
| __ashrdi3:
| subfic r6,r5,32
| srw r4,r4,r5 # LSW = count > 31 ? 0 : LSW >> count
| addi r7,r5,32 # could be xori, or addi with -32
| slw r6,r3,r6 # t1 = count > 31 ? 0 : MSW << (32-count)
| rlwinm r8,r7,0,32 # t3 = (count < 32) ? 32 : 0
| sraw r7,r3,r7 # t2 = MSW >> (count-32)
| or r4,r4,r6 # LSW |= t1
| slw r7,r7,r8 # t2 = (count < 32) ? 0 : t2
| sraw r3,r3,r5 # MSW = MSW >> count
| or r4,r4,r7 # LSW |= t2
| blr
|
| .globl __ashldi3
| __ashldi3:
| subfic r6,r5,32
| slw r3,r3,r5 # MSW = count > 31 ? 0 : MSW << count
| addi r7,r5,32 # could be xori, or addi with -32
| srw r6,r4,r6 # t1 = count > 31 ? 0 : LSW >> (32-count)
| slw r7,r4,r7 # t2 = count < 32 ? 0 : LSW << (count-32)
| or r3,r3,r6 # MSW |= t1
| slw r4,r4,r5 # LSW = LSW << count
| or r3,r3,r7 # MSW |= t2
| blr
|
| .globl __lshrdi3
| __lshrdi3:
| subfic r6,r5,32
| srw r4,r4,r5 # LSW = count > 31 ? 0 : LSW >> count
| addi r7,r5,32 # could be xori, or addi with -32
| slw r6,r3,r6 # t1 = count > 31 ? 0 : MSW << (32-count)
| srw r7,r3,r7 # t2 = count < 32 ? 0 : MSW >> (count-32)
| or r4,r4,r6 # LSW |= t1
| srw r3,r3,r5 # MSW = MSW >> count
| or r4,r4,r7 # LSW |= t2
| blr
|
|
