98 lines
3.1 KiB
NASM
98 lines
3.1 KiB
NASM
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dnl ARM mpn_invert_limb -- Invert a normalized limb.
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dnl Copyright 2001 Free Software Foundation, Inc.
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dnl This file is part of the GNU MP Library.
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dnl The GNU MP Library is free software; you can redistribute it and/or modify
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dnl it under the terms of the GNU Lesser General Public License as published
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dnl by the Free Software Foundation; either version 2.1 of the License, or (at
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dnl your option) any later version.
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dnl The GNU MP Library is distributed in the hope that it will be useful, but
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dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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dnl License for more details.
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dnl You should have received a copy of the GNU Lesser General Public License
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dnl along with the GNU MP Library; see the file COPYING.LIB. If not, write
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dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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dnl Boston, MA 02110-1301, USA.
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include(`../config.m4')
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C INPUT PARAMETERS
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define(`d',`r0') C number to be inverted
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PROLOGUE(mpn_invert_limb)
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stmfd sp!, {r4, lr}
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mov r3, d, lsr #23
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sub r3, r3, #256
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add r2, pc, #invtab-.-8
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mov r3, r3, lsl #1
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ldrh r1, [r2, r3] C get initial approximation from table
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mov r2, r1, lsl #6 C start iteration 1
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mul ip, r2, r2
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umull lr, r4, ip, d
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mov r2, r4, lsl #1
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rsb r2, r2, r1, lsl #23 C iteration 1 complete
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umull ip, r3, r2, r2 C start iteration 2
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umull lr, r4, r3, d
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umull r3, r1, ip, d
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adds lr, lr, r1
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addcs r4, r4, #1
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mov r3, lr, lsr #30
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orr r4, r3, r4, lsl #2
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mov lr, lr, lsl #2
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cmn lr, #1
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rsc r2, r4, r2, lsl #2 C iteration 2 complete
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umull ip, r1, d, r2 C start adjustment step
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add r1, r1, d
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cmn r1, #1
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beq L(1)
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adds ip, ip, d
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adc r1, r1, #0
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add r2, r2, #1
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L(1):
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adds r3, ip, d
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adcs r1, r1, #0
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moveq r0, r2
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addne r0, r2, #1
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ldmfd sp!, {r4, pc}
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invtab:
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.short 1023,1020,1016,1012,1008,1004,1000,996
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.short 992,989,985,981,978,974,970,967
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.short 963,960,956,953,949,946,942,939
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.short 936,932,929,926,923,919,916,913
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.short 910,907,903,900,897,894,891,888
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.short 885,882,879,876,873,870,868,865
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.short 862,859,856,853,851,848,845,842
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.short 840,837,834,832,829,826,824,821
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.short 819,816,814,811,809,806,804,801
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.short 799,796,794,791,789,787,784,782
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.short 780,777,775,773,771,768,766,764
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.short 762,759,757,755,753,751,748,746
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.short 744,742,740,738,736,734,732,730
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.short 728,726,724,722,720,718,716,714
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.short 712,710,708,706,704,702,700,699
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.short 697,695,693,691,689,688,686,684
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.short 682,680,679,677,675,673,672,670
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.short 668,667,665,663,661,660,658,657
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.short 655,653,652,650,648,647,645,644
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.short 642,640,639,637,636,634,633,631
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.short 630,628,627,625,624,622,621,619
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.short 618,616,615,613,612,611,609,608
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.short 606,605,604,602,601,599,598,597
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.short 595,594,593,591,590,589,587,586
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.short 585,583,582,581,579,578,577,576
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.short 574,573,572,571,569,568,567,566
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.short 564,563,562,561,560,558,557,556
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.short 555,554,553,551,550,549,548,547
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.short 546,544,543,542,541,540,539,538
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.short 537,536,534,533,532,531,530,529
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.short 528,527,526,525,524,523,522,521
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.short 520,519,518,517,516,515,514,513
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EPILOGUE(mpn_invert_limb)
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