blob: bbcb8a4cc12107293ea7bbee414855510eba8479 [file] [log] [blame]
 /* * 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. * * 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. */ #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