github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/m88k/sub_n.s (about)

     1  ; mc88100 mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
     2  ; store difference in a third limb vector.
     3  
     4  ; Copyright 1992, 1994, 1996, 2000 Free Software Foundation, Inc.
     5  
     6  ;  This file is part of the GNU MP Library.
     7  ;
     8  ;  The GNU MP Library is free software; you can redistribute it and/or modify
     9  ;  it under the terms of either:
    10  ;
    11  ;    * the GNU Lesser General Public License as published by the Free
    12  ;      Software Foundation; either version 3 of the License, or (at your
    13  ;      option) any later version.
    14  ;
    15  ;  or
    16  ;
    17  ;    * the GNU General Public License as published by the Free Software
    18  ;      Foundation; either version 2 of the License, or (at your option) any
    19  ;      later version.
    20  ;
    21  ;  or both in parallel, as here.
    22  ;
    23  ;  The GNU MP Library is distributed in the hope that it will be useful, but
    24  ;  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    25  ;  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    26  ;  for more details.
    27  ;
    28  ;  You should have received copies of the GNU General Public License and the
    29  ;  GNU Lesser General Public License along with the GNU MP Library.  If not,
    30  ;  see https://www.gnu.org/licenses/.
    31  
    32  
    33  ; INPUT PARAMETERS
    34  ; res_ptr	r2
    35  ; s1_ptr	r3
    36  ; s2_ptr	r4
    37  ; size		r5
    38  
    39  ; This code has been optimized to run one instruction per clock, avoiding
    40  ; load stalls and writeback contention.  As a result, the instruction
    41  ; order is not always natural.
    42  
    43  ; The speed is about 4.6 clocks/limb + 18 clocks/limb-vector on an 88100,
    44  ; but on the 88110, it seems to run much slower, 6.6 clocks/limb.
    45  
    46  	text
    47  	align	 16
    48  	global	 ___gmpn_sub_n
    49  ___gmpn_sub_n:
    50  	ld	r6,r3,0			; read first limb from s1_ptr
    51  	extu	r10,r5,3
    52  	ld	r7,r4,0			; read first limb from s2_ptr
    53  
    54  	subu	r5,r0,r5
    55  	mak	r5,r5,3<4>
    56  	bcnd.n	eq0,r5,Lzero
    57  	subu.co	r0,r0,r0		; initialize carry
    58  
    59  	or	r12,r0,lo16(Lbase)
    60  	or.u	r12,r12,hi16(Lbase)
    61  	addu	r12,r12,r5		; r12 is address for entering in loop
    62  
    63  	extu	r5,r5,2			; divide by 4
    64  	subu	r2,r2,r5		; adjust res_ptr
    65  	subu	r3,r3,r5		; adjust s1_ptr
    66  	subu	r4,r4,r5		; adjust s2_ptr
    67  
    68  	or	r8,r6,r0
    69  
    70  	jmp.n	r12
    71  	 or	r9,r7,r0
    72  
    73  Loop:	addu	r3,r3,32
    74  	st	r8,r2,28
    75  	addu	r4,r4,32
    76  	ld	r6,r3,0
    77  	addu	r2,r2,32
    78  	ld	r7,r4,0
    79  Lzero:	subu	r10,r10,1		; subtract 0 + 8r limbs (adj loop cnt)
    80  Lbase:	ld	r8,r3,4
    81  	subu.cio r6,r6,r7
    82  	ld	r9,r4,4
    83  	st	r6,r2,0
    84  	ld	r6,r3,8			; subtract 7 + 8r limbs
    85  	subu.cio r8,r8,r9
    86  	ld	r7,r4,8
    87  	st	r8,r2,4
    88  	ld	r8,r3,12		; subtract 6 + 8r limbs
    89  	subu.cio r6,r6,r7
    90  	ld	r9,r4,12
    91  	st	r6,r2,8
    92  	ld	r6,r3,16		; subtract 5 + 8r limbs
    93  	subu.cio r8,r8,r9
    94  	ld	r7,r4,16
    95  	st	r8,r2,12
    96  	ld	r8,r3,20		; subtract 4 + 8r limbs
    97  	subu.cio r6,r6,r7
    98  	ld	r9,r4,20
    99  	st	r6,r2,16
   100  	ld	r6,r3,24		; subtract 3 + 8r limbs
   101  	subu.cio r8,r8,r9
   102  	ld	r7,r4,24
   103  	st	r8,r2,20
   104  	ld	r8,r3,28		; subtract 2 + 8r limbs
   105  	subu.cio r6,r6,r7
   106  	ld	r9,r4,28
   107  	st	r6,r2,24
   108  	bcnd.n	ne0,r10,Loop		; subtract 1 + 8r limbs
   109  	 subu.cio r8,r8,r9
   110  
   111  	st	r8,r2,28		; store most significant limb
   112  
   113  	addu.ci r2,r0,r0		; return carry-out from most sign. limb
   114  	jmp.n	 r1
   115  	 xor	r2,r2,1