18c2ecf20Sopenharmony_ci/* SPDX-License-Identifier: GPL-2.0-or-later */ 28c2ecf20Sopenharmony_ci/* 38c2ecf20Sopenharmony_ci * Divide a 64-bit unsigned number by a 32-bit unsigned number. 48c2ecf20Sopenharmony_ci * This routine assumes that the top 32 bits of the dividend are 58c2ecf20Sopenharmony_ci * non-zero to start with. 68c2ecf20Sopenharmony_ci * On entry, r3 points to the dividend, which get overwritten with 78c2ecf20Sopenharmony_ci * the 64-bit quotient, and r4 contains the divisor. 88c2ecf20Sopenharmony_ci * On exit, r3 contains the remainder. 98c2ecf20Sopenharmony_ci * 108c2ecf20Sopenharmony_ci * Copyright (C) 2002 Paul Mackerras, IBM Corp. 118c2ecf20Sopenharmony_ci */ 128c2ecf20Sopenharmony_ci#include <asm/ppc_asm.h> 138c2ecf20Sopenharmony_ci#include <asm/processor.h> 148c2ecf20Sopenharmony_ci 158c2ecf20Sopenharmony_ci_GLOBAL(__div64_32) 168c2ecf20Sopenharmony_ci lwz r5,0(r3) # get the dividend into r5/r6 178c2ecf20Sopenharmony_ci lwz r6,4(r3) 188c2ecf20Sopenharmony_ci cmplw r5,r4 198c2ecf20Sopenharmony_ci li r7,0 208c2ecf20Sopenharmony_ci li r8,0 218c2ecf20Sopenharmony_ci blt 1f 228c2ecf20Sopenharmony_ci divwu r7,r5,r4 # if dividend.hi >= divisor, 238c2ecf20Sopenharmony_ci mullw r0,r7,r4 # quotient.hi = dividend.hi / divisor 248c2ecf20Sopenharmony_ci subf. r5,r0,r5 # dividend.hi %= divisor 258c2ecf20Sopenharmony_ci beq 3f 268c2ecf20Sopenharmony_ci1: mr r11,r5 # here dividend.hi != 0 278c2ecf20Sopenharmony_ci andis. r0,r5,0xc000 288c2ecf20Sopenharmony_ci bne 2f 298c2ecf20Sopenharmony_ci cntlzw r0,r5 # we are shifting the dividend right 308c2ecf20Sopenharmony_ci li r10,-1 # to make it < 2^32, and shifting 318c2ecf20Sopenharmony_ci srw r10,r10,r0 # the divisor right the same amount, 328c2ecf20Sopenharmony_ci addc r9,r4,r10 # rounding up (so the estimate cannot 338c2ecf20Sopenharmony_ci andc r11,r6,r10 # ever be too large, only too small) 348c2ecf20Sopenharmony_ci andc r9,r9,r10 358c2ecf20Sopenharmony_ci addze r9,r9 368c2ecf20Sopenharmony_ci or r11,r5,r11 378c2ecf20Sopenharmony_ci rotlw r9,r9,r0 388c2ecf20Sopenharmony_ci rotlw r11,r11,r0 398c2ecf20Sopenharmony_ci divwu r11,r11,r9 # then we divide the shifted quantities 408c2ecf20Sopenharmony_ci2: mullw r10,r11,r4 # to get an estimate of the quotient, 418c2ecf20Sopenharmony_ci mulhwu r9,r11,r4 # multiply the estimate by the divisor, 428c2ecf20Sopenharmony_ci subfc r6,r10,r6 # take the product from the divisor, 438c2ecf20Sopenharmony_ci add r8,r8,r11 # and add the estimate to the accumulated 448c2ecf20Sopenharmony_ci subfe. r5,r9,r5 # quotient 458c2ecf20Sopenharmony_ci bne 1b 468c2ecf20Sopenharmony_ci3: cmplw r6,r4 478c2ecf20Sopenharmony_ci blt 4f 488c2ecf20Sopenharmony_ci divwu r0,r6,r4 # perform the remaining 32-bit division 498c2ecf20Sopenharmony_ci mullw r10,r0,r4 # and get the remainder 508c2ecf20Sopenharmony_ci add r8,r8,r0 518c2ecf20Sopenharmony_ci subf r6,r10,r6 528c2ecf20Sopenharmony_ci4: stw r7,0(r3) # return the quotient in *r3 538c2ecf20Sopenharmony_ci stw r8,4(r3) 548c2ecf20Sopenharmony_ci mr r3,r6 # return the remainder in r3 558c2ecf20Sopenharmony_ci blr 56