Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

Open Menu /external/lgpl3/gmp/dist/mpn/m88k/mul_1.s 
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
; mc88100 __gmpn_mul_1 -- Multiply a limb vector with a single limb and
; store the product in a second limb vector.

; Copyright 1992, 1994, 1995, 2000 Free Software Foundation, Inc.

;  This file is part of the GNU MP Library.
;
;  The GNU MP Library is free software; you can redistribute it and/or modify
;  it under the terms of either:
;
;    * the GNU Lesser General Public License as published by the Free
;      Software Foundation; either version 3 of the License, or (at your
;      option) any later version.
;
;  or
;
;    * the GNU General Public License as published by the Free Software
;      Foundation; either version 2 of the License, or (at your option) any
;      later version.
;
;  or both in parallel, as here.
;
;  The GNU MP Library is distributed in the hope that it will be useful, but
;  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
;  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
;  for more details.
;
;  You should have received copies of the GNU General Public License and the
;  GNU Lesser General Public License along with the GNU MP Library.  If not,
;  see https://www.gnu.org/licenses/.


; INPUT PARAMETERS
; res_ptr	r2
; s1_ptr	r3
; size		r4
; s2_limb	r5

; Common overhead is about 11 cycles/invocation.

; The speed for S2_LIMB >= 0x10000 is approximately 21 cycles/limb.  (The
; pipeline stalls 2 cycles due to WB contention.)

; The speed for S2_LIMB < 0x10000 is approximately 16 cycles/limb.  (The
; pipeline stalls 2 cycles due to WB contention and 1 cycle due to latency.)

; To enhance speed:
; 1. Unroll main loop 4-8 times.
; 2. Schedule code to avoid WB contention.  It might be tempting to move the
;    ld instruction in the loops down to save 2 cycles (less WB contention),
;    but that looses because the ultimate value will be read from outside
;    the allocated space.  But if we handle the ultimate multiplication in
;    the tail, we can do this.
; 3. Make the multiplication with less instructions.  I think the code for
;    (S2_LIMB >= 0x10000) is not minimal.
; With these techniques the (S2_LIMB >= 0x10000) case would run in 17 or
; less cycles/limb; the (S2_LIMB < 0x10000) case would run in 11
; cycles/limb.  (Assuming infinite unrolling.)

	text
	align	 16
	global	 ___gmpn_mul_1
___gmpn_mul_1:

	; Make S1_PTR and RES_PTR point at the end of their blocks
	; and negate SIZE.
	lda	 r3,r3[r4]
	lda	 r6,r2[r4]	; RES_PTR in r6 since r2 is retval
	subu	 r4,r0,r4

	addu.co	 r2,r0,r0	; r2 = cy = 0
	ld	 r9,r3[r4]
	mask	 r7,r5,0xffff	; r7 = lo(S2_LIMB)
	extu	 r8,r5,16	; r8 = hi(S2_LIMB)
	bcnd.n	 eq0,r8,Lsmall	; jump if (hi(S2_LIMB) == 0)
	 subu	 r6,r6,4

; General code for any value of S2_LIMB.

	; Make a stack frame and save r25 and r26
	subu	 r31,r31,16
	st.d	 r25,r31,8

	; Enter the loop in the middle
	br.n	L1
	addu	 r4,r4,1

Loop:	ld	 r9,r3[r4]
	st	 r26,r6[r4]
; bcnd	ne0,r0,0		; bubble
	addu	 r4,r4,1
L1:	mul	 r26,r9,r5	; low word of product	mul_1	WB ld
	mask	 r12,r9,0xffff	; r12 = lo(s1_limb)	mask_1
	mul	 r11,r12,r7	; r11 =  prod_0		mul_2	WB mask_1
	mul	 r10,r12,r8	; r10 = prod_1a		mul_3
	extu	 r13,r9,16	; r13 = hi(s1_limb)	extu_1	WB mul_1
	mul	 r12,r13,r7	; r12 = prod_1b		mul_4	WB extu_1
	mul	 r25,r13,r8	; r25  = prod_2		mul_5	WB mul_2
	extu	 r11,r11,16	; r11 = hi(prod_0)	extu_2	WB mul_3
	addu	 r10,r10,r11	;			addu_1	WB extu_2
; bcnd	ne0,r0,0		; bubble			WB addu_1
	addu.co	 r10,r10,r12	;				WB mul_4
	mask.u	 r10,r10,0xffff	; move the 16 most significant bits...
	addu.ci	 r10,r10,r0	; ...to the low half of the word...
	rot	 r10,r10,16	; ...and put carry in pos 16.
	addu.co	 r26,r26,r2	; add old carry limb
	bcnd.n	 ne0,r4,Loop
	 addu.ci r2,r25,r10	; compute new carry limb

	st	 r26,r6[r4]
	ld.d	 r25,r31,8
	jmp.n	 r1
	 addu	 r31,r31,16

; Fast code for S2_LIMB < 0x10000
Lsmall:
	; Enter the loop in the middle
	br.n	SL1
	addu	 r4,r4,1

SLoop:	ld	 r9,r3[r4]	;
	st	 r8,r6[r4]	;
	addu	 r4,r4,1	;
SL1:	mul	 r8,r9,r5	; low word of product
	mask	 r12,r9,0xffff	; r12 = lo(s1_limb)
	extu	 r13,r9,16	; r13 = hi(s1_limb)
	mul	 r11,r12,r7	; r11 =  prod_0
	mul	 r12,r13,r7	; r12 = prod_1b
	addu.cio r8,r8,r2	; add old carry limb
	extu	 r10,r11,16	; r11 = hi(prod_0)
	addu	 r10,r10,r12	;
	bcnd.n	 ne0,r4,SLoop
	extu	 r2,r10,16	; r2 = new carry limb

	jmp.n	 r1
	st	 r8,r6[r4]