1 ; mc88100 __mpn_mul_1
-- Multiply
a limb vector with
a single limb
and
2 ; store the product in
a second limb vector.
4 ; Copyright
(C
) 1992, 1994 Free Software Foundation
, Inc.
6 ; This file is part of the GNU MP Library.
8 ; The GNU MP Library is free software; you can redistribute it
and/or modify
9 ; it under the terms of the GNU Library General Public License as published by
10 ; the Free Software Foundation; either version
2 of the License
, or (at your
11 ; option
) any later version.
13 ; The GNU MP Library is distributed in the hope that it will
be useful
, but
14 ; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 ;
or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU Library General Public
16 ; License for more details.
18 ; You should have received
a copy of the GNU Library General Public License
19 ; along with the GNU MP Library; see the file COPYING.LIB. If
not, write to
20 ; the Free Software Foundation
, Inc.
, 675 Mass Ave
, Cambridge
, MA
02139, USA.
29 ; Common overhead is about
11 cycles
/invocation.
31 ; The speed for S2_LIMB
>= 0x10000 is approximately
21 cycles
/limb.
(The
32 ; pipeline stalls
2 cycles due to WB contention.
)
34 ; The speed for S2_LIMB
< 0x10000 is approximately
16 cycles
/limb.
(The
35 ; pipeline stalls
2 cycles due to WB contention
and 1 cycle due to latency.
)
38 ;
1. Unroll main loop 4-8 times.
39 ;
2. Schedule code to avoid WB contention. It might be tempting to move the
40 ;
ld instruction in the loops down to save
2 cycles
(less WB contention
),
41 ; but that looses because the ultimate value will
be read from outside
42 ; the allocated space. But if we handle the ultimate multiplication in
43 ; the tail
, we can do this.
44 ;
3. Make the multiplication with less instructions. I think the code for
45 ;
(S2_LIMB
>= 0x10000) is
not minimal.
46 ; With these techniques the
(S2_LIMB
>= 0x10000) case would run in
17 or
47 ; less cycles
/limb; the
(S2_LIMB
< 0x10000) case would run in
11
48 ; cycles
/limb.
(Assuming infinite unrolling.
)
55 ; Make S1_PTR
and RES_PTR point at the end of their blocks
58 lda
r6,r2[r4] ; RES_PTR in
r6 since
r2 is retval
61 addu.co
r2,r0,r0 ;
r2 = cy
= 0
63 mask
r7,r5,0xffff ;
r7 = lo
(S2_LIMB
)
64 extu
r8,r5,16 ;
r8 = hi
(S2_LIMB
)
65 bcnd.n eq0
,r8,Lsmall ; jump if
(hi
(S2_LIMB
) == 0)
68 ; General code for any value of S2_LIMB.
70 ; Make
a stack frame
and save
r25 and r26
74 ; Enter the loop in the middle
81 ; bcnd ne0
,r0,0 ; bubble
83 L1
: mul r26,r9,r5 ; low word of product mul_1 WB
ld
84 mask
r12,r9,0xffff ;
r12 = lo
(s1_limb
) mask_1
85 mul r11,r12,r7 ;
r11 = prod_0 mul_2 WB mask_1
86 mul r10,r12,r8 ;
r10 = prod_1a mul_3
87 extu
r13,r9,16 ;
r13 = hi
(s1_limb
) extu_1 WB mul_1
88 mul r12,r13,r7 ;
r12 = prod_1b mul_4 WB extu_1
89 mul r25,r13,r8 ;
r25 = prod_2 mul_5 WB mul_2
90 extu
r11,r11,16 ;
r11 = hi
(prod_0
) extu_2 WB mul_3
91 addu
r10,r10,r11 ; addu_1 WB extu_2
92 ; bcnd ne0
,r0,0 ; bubble WB addu_1
93 addu.co
r10,r10,r12 ; WB mul_4
94 mask.u
r10,r10,0xffff ; move the
16 most significant bits.
..
95 addu.ci
r10,r10,r0 ;
...to the low half of the word...
96 rot
r10,r10,16 ;
...and put carry in pos 16.
97 addu.co
r26,r26,r2 ;
add old carry limb
99 addu.ci
r2,r25,r10 ; compute new carry limb
106 ; Fast code for S2_LIMB
< 0x10000
108 ; Enter the loop in the middle
116 SL1
: mul r8,r9,r5 ; low word of product
117 mask
r12,r9,0xffff ;
r12 = lo
(s1_limb
)
118 extu
r13,r9,16 ;
r13 = hi
(s1_limb
)
119 mul r11,r12,r7 ;
r11 = prod_0
120 mul r12,r13,r7 ;
r12 = prod_1b
121 addu.cio
r8,r8,r2 ;
add old carry limb
122 extu
r10,r11,16 ;
r11 = hi
(prod_0
)
125 extu
r2,r10,16 ;
r2 = new carry limb