Imported gcc-4.4.3

[msp430-gcc.git] / gmp / mpn / arm / udiv.asm

diff --git a/gmp/mpn/arm/udiv.asm b/gmp/mpn/arm/udiv.asm
new file mode 100644 (file)
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+++ b/gmp/mpn/arm/udiv.asm
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+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)