X-Git-Url: https://oss.titaniummirror.com/gitweb?a=blobdiff_plain;f=gmp%2Fmpn%2Farm%2Fudiv.asm;fp=gmp%2Fmpn%2Farm%2Fudiv.asm;h=9434a4f2b6a018245352f7ffe6499ce78d6f01f0;hb=6fed43773c9b0ce596dca5686f37ac3fc0fa11c0;hp=0000000000000000000000000000000000000000;hpb=27b11d56b743098deb193d510b337ba22dc52e5c;p=msp430-gcc.git diff --git a/gmp/mpn/arm/udiv.asm b/gmp/mpn/arm/udiv.asm new file mode 100644 index 00000000..9434a4f2 --- /dev/null +++ b/gmp/mpn/arm/udiv.asm @@ -0,0 +1,93 @@ +dnl ARM mpn_udiv_qrnnd -- divide a two limb dividend and a one limb divisor. +dnl Return quotient and store remainder through a supplied pointer. + +dnl Copyright 2001 Free Software Foundation, Inc. + +dnl This file is part of the GNU MP Library. + +dnl The GNU MP Library is free software; you can redistribute it and/or modify +dnl it under the terms of the GNU Lesser General Public License as published +dnl by the Free Software Foundation; either version 3 of the License, or (at +dnl your option) any later version. + +dnl The GNU MP Library is distributed in the hope that it will be useful, but +dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public +dnl License for more details. + +dnl You should have received a copy of the GNU Lesser General Public License +dnl along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. + +include(`../config.m4') + +C INPUT PARAMETERS +define(`rem_ptr',`r0') +define(`n1',`r1') +define(`n0',`r2') +define(`d',`r3') + +C divstep -- develop one quotient bit. Dividend in $1$2, divisor in $3. +C Quotient bit is shifted into $2. +define(`divstep', + `adcs $2, $2, $2 + adc $1, $1, $1 + cmp $1, $3 + subcs $1, $1, $3') + +ASM_START() +PROLOGUE(mpn_udiv_qrnnd) + mov r12, #8 C loop counter for both loops below + cmp d, #0x80000000 C check divisor msb and clear carry + bcs L(_large_divisor) + +L(oop): divstep(n1,n0,d) + divstep(n1,n0,d) + divstep(n1,n0,d) + divstep(n1,n0,d) + sub r12, r12, #1 + teq r12, #0 + bne L(oop) + + str n1, [ rem_ptr ] C store remainder + adc r0, n0, n0 C quotient: add last carry from divstep + mov pc, lr + +L(_large_divisor): + stmfd sp!, { r8, lr } + + and r8, n0, #1 C save lsb of dividend + mov lr, n1, lsl #31 + orrs n0, lr, n0, lsr #1 C n0 = lo(n1n0 >> 1) + mov n1, n1, lsr #1 C n1 = hi(n1n0 >> 1) + + and lr, d, #1 C save lsb of divisor + movs d, d, lsr #1 C d = floor(orig_d / 2) + adc d, d, #0 C d = ceil(orig_d / 2) + +L(oop2): + divstep(n1,n0,d) + divstep(n1,n0,d) + divstep(n1,n0,d) + divstep(n1,n0,d) + sub r12, r12, #1 + teq r12, #0 + bne L(oop2) + + adc n0, n0, n0 C shift and add last carry from divstep + add n1, r8, n1, lsl #1 C shift in omitted dividend lsb + tst lr, lr C test saved divisor lsb + beq L(_even_divisor) + + rsb d, lr, d, lsl #1 C restore orig d value + adds n1, n1, n0 C fix remainder for omitted divisor lsb + addcs n0, n0, #1 C adjust quotient if rem. fix carried + subcs n1, n1, d C adjust remainder accordingly + cmp n1, d C remainder >= divisor? + subcs n1, n1, d C adjust remainder + addcs n0, n0, #1 C adjust quotient + +L(_even_divisor): + str n1, [ rem_ptr ] C store remainder + mov r0, n0 C quotient + ldmfd sp!, { r8, pc } +EPILOGUE(mpn_udiv_qrnnd)