github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/m88k/mul_1.s (about)

     1  ; mc88100 __gmpn_mul_1 -- Multiply a limb vector with a single limb and
     2  ; store the product in a second limb vector.
     3  
     4  ; Copyright 1992, 1994, 1995, 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  ; size		r4
    37  ; s2_limb	r5
    38  
    39  ; Common overhead is about 11 cycles/invocation.
    40  
    41  ; The speed for S2_LIMB >= 0x10000 is approximately 21 cycles/limb.  (The
    42  ; pipeline stalls 2 cycles due to WB contention.)
    43  
    44  ; The speed for S2_LIMB < 0x10000 is approximately 16 cycles/limb.  (The
    45  ; pipeline stalls 2 cycles due to WB contention and 1 cycle due to latency.)
    46  
    47  ; To enhance speed:
    48  ; 1. Unroll main loop 4-8 times.
    49  ; 2. Schedule code to avoid WB contention.  It might be tempting to move the
    50  ;    ld instruction in the loops down to save 2 cycles (less WB contention),
    51  ;    but that looses because the ultimate value will be read from outside
    52  ;    the allocated space.  But if we handle the ultimate multiplication in
    53  ;    the tail, we can do this.
    54  ; 3. Make the multiplication with less instructions.  I think the code for
    55  ;    (S2_LIMB >= 0x10000) is not minimal.
    56  ; With these techniques the (S2_LIMB >= 0x10000) case would run in 17 or
    57  ; less cycles/limb; the (S2_LIMB < 0x10000) case would run in 11
    58  ; cycles/limb.  (Assuming infinite unrolling.)
    59  
    60  	text
    61  	align	 16
    62  	global	 ___gmpn_mul_1
    63  ___gmpn_mul_1:
    64  
    65  	; Make S1_PTR and RES_PTR point at the end of their blocks
    66  	; and negate SIZE.
    67  	lda	 r3,r3[r4]
    68  	lda	 r6,r2[r4]	; RES_PTR in r6 since r2 is retval
    69  	subu	 r4,r0,r4
    70  
    71  	addu.co	 r2,r0,r0	; r2 = cy = 0
    72  	ld	 r9,r3[r4]
    73  	mask	 r7,r5,0xffff	; r7 = lo(S2_LIMB)
    74  	extu	 r8,r5,16	; r8 = hi(S2_LIMB)
    75  	bcnd.n	 eq0,r8,Lsmall	; jump if (hi(S2_LIMB) == 0)
    76  	 subu	 r6,r6,4
    77  
    78  ; General code for any value of S2_LIMB.
    79  
    80  	; Make a stack frame and save r25 and r26
    81  	subu	 r31,r31,16
    82  	st.d	 r25,r31,8
    83  
    84  	; Enter the loop in the middle
    85  	br.n	L1
    86  	addu	 r4,r4,1
    87  
    88  Loop:	ld	 r9,r3[r4]
    89  	st	 r26,r6[r4]
    90  ; bcnd	ne0,r0,0		; bubble
    91  	addu	 r4,r4,1
    92  L1:	mul	 r26,r9,r5	; low word of product	mul_1	WB ld
    93  	mask	 r12,r9,0xffff	; r12 = lo(s1_limb)	mask_1
    94  	mul	 r11,r12,r7	; r11 =  prod_0		mul_2	WB mask_1
    95  	mul	 r10,r12,r8	; r10 = prod_1a		mul_3
    96  	extu	 r13,r9,16	; r13 = hi(s1_limb)	extu_1	WB mul_1
    97  	mul	 r12,r13,r7	; r12 = prod_1b		mul_4	WB extu_1
    98  	mul	 r25,r13,r8	; r25  = prod_2		mul_5	WB mul_2
    99  	extu	 r11,r11,16	; r11 = hi(prod_0)	extu_2	WB mul_3
   100  	addu	 r10,r10,r11	;			addu_1	WB extu_2
   101  ; bcnd	ne0,r0,0		; bubble			WB addu_1
   102  	addu.co	 r10,r10,r12	;				WB mul_4
   103  	mask.u	 r10,r10,0xffff	; move the 16 most significant bits...
   104  	addu.ci	 r10,r10,r0	; ...to the low half of the word...
   105  	rot	 r10,r10,16	; ...and put carry in pos 16.
   106  	addu.co	 r26,r26,r2	; add old carry limb
   107  	bcnd.n	 ne0,r4,Loop
   108  	 addu.ci r2,r25,r10	; compute new carry limb
   109  
   110  	st	 r26,r6[r4]
   111  	ld.d	 r25,r31,8
   112  	jmp.n	 r1
   113  	 addu	 r31,r31,16
   114  
   115  ; Fast code for S2_LIMB < 0x10000
   116  Lsmall:
   117  	; Enter the loop in the middle
   118  	br.n	SL1
   119  	addu	 r4,r4,1
   120  
   121  SLoop:	ld	 r9,r3[r4]	;
   122  	st	 r8,r6[r4]	;
   123  	addu	 r4,r4,1	;
   124  SL1:	mul	 r8,r9,r5	; low word of product
   125  	mask	 r12,r9,0xffff	; r12 = lo(s1_limb)
   126  	extu	 r13,r9,16	; r13 = hi(s1_limb)
   127  	mul	 r11,r12,r7	; r11 =  prod_0
   128  	mul	 r12,r13,r7	; r12 = prod_1b
   129  	addu.cio r8,r8,r2	; add old carry limb
   130  	extu	 r10,r11,16	; r11 = hi(prod_0)
   131  	addu	 r10,r10,r12	;
   132  	bcnd.n	 ne0,r4,SLoop
   133  	extu	 r2,r10,16	; r2 = new carry limb
   134  
   135  	jmp.n	 r1
   136  	st	 r8,r6[r4]