sysdeps/arm/add_n.S

   1 /* mpn_add_n -- add (or subtract) bignums.
   2    Copyright (C) 2013-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <sysdep.h>
  20 #include <arm-features.h>
  21
  22         .syntax unified
  23         .text
  24
  25 #ifdef USE_AS_SUB_N
  26 # define INITC  cmp r0, r0
  27 # define OPC    sbcs
  28 # define RETC   sbc r0, r0, r0; neg r0, r0
  29 # define FUNC   __mpn_sub_n
  30 #else
  31 # define INITC  cmn r0, #0
  32 # define OPC    adcs
  33 # define RETC   mov r0, #0; adc r0, r0, r0
  34 # define FUNC   __mpn_add_n
  35 #endif
  36
  37 /* mp_limb_t mpn_add_n(res_ptr, src1_ptr, src2_ptr, size) */
  38
  39 ENTRY (FUNC)
  40         push    { r4, r5, r6, r7, r8, r10, lr }
  41         cfi_adjust_cfa_offset (28)
  42         cfi_rel_offset (r4, 0)
  43         cfi_rel_offset (r5, 4)
  44         cfi_rel_offset (r6, 8)
  45         cfi_rel_offset (r7, 12)
  46         cfi_rel_offset (r8, 16)
  47         cfi_rel_offset (r10, 20)
  48         cfi_rel_offset (lr, 24)
  49
  50         INITC                           /* initialize carry flag */
  51         tst     r3, #1                  /* count & 1 == 1? */
  52         add     lr, r1, r3, lsl #2      /* compute end src1 */
  53         beq     1f
  54
  55         sfi_breg r1, \
  56         ldr     r4, [\B], #4            /* do one to make count even */
  57         sfi_breg r2, \
  58         ldr     r5, [\B], #4
  59         OPC     r4, r4, r5
  60         teq     r1, lr                  /* end of count? (preserve carry) */
  61         sfi_breg r0, \
  62         str     r4, [\B], #4
  63         beq     9f
  64 1:
  65         tst     r3, #2                  /* count & 2 == 2?  */
  66         beq     2f
  67         sfi_breg r1, \
  68         ldm     \B!, { r4, r5 }         /* do two to make count 0 mod 4 */
  69         sfi_breg r2, \
  70         ldm     \B!, { r6, r7 }
  71         OPC     r4, r4, r6
  72         OPC     r5, r5, r7
  73         teq     r1, lr                  /* end of count? */
  74         sfi_breg r0, \
  75         stm     \B!, { r4, r5 }
  76         beq     9f
  77 2:
  78         sfi_breg r1, \
  79         ldm     \B!, { r3, r5, r7, r10 }        /* do four each loop */
  80         sfi_breg r2, \
  81         ldm     \B!, { r4, r6, r8, ip }
  82         OPC     r3, r3, r4
  83         OPC     r5, r5, r6
  84         OPC     r7, r7, r8
  85         OPC     r10, r10, ip
  86         teq     r1, lr
  87         sfi_breg r0, \
  88         stm     \B!, { r3, r5, r7, r10 }
  89         bne     2b
  90
  91 9:
  92         RETC                            /* copy carry out */
  93 #ifndef ARM_ALWAYS_BX
  94         pop     { r4, r5, r6, r7, r8, r10, pc }
  95 #else
  96         pop     { r4, r5, r6, r7, r8, r10, lr }
  97         bx      lr
  98 #endif
  99 END (FUNC)