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Unroll SHA-1 loop with variables substituted to avoid cycling values around.

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SHA-1 has five state variables (a,b,c,d,e), and each iteration of the core loop cycles their values around (e.g. a->b), in some cases with modifications. By unrolling the loop by a factor of five and appropriately substituting the values operated on in each iteration, we can avoid actually doing the copies implied by this cycling, which gives a fairly significant performance gain.
This commit is contained in:
Stephen Heumann 2017-06-30 00:15:47 -05:00
parent aab47e38e7
commit 2d8c85bd98
1 changed files with 74 additions and 76 deletions
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150
sha1.macros
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@ -20,64 +20,64 @@
* Left-rotate 32-bit value in &loc (DP or 16-bit address) by &n positions
macro
ROTL4 &loc,&n
aif &n>16,.dorotr
aif &n>16,.dorotr2
lda &loc
lcla &i
&i seta &n
.rotlloop
.rotlloop2
asl a ;to set carry
rol &loc+2
rol &loc
&i seta &i-1
aif &i>0,.rotlloop
ago .end
.dorotr
aif &i>0,.rotlloop2
ago .end2
.dorotr2
ROTR4 &loc,32-&n
.end
.end2
mend
* &to := &from ROTR4 &n
macro
ROTR4MOVE &to,&from,&n
aif &n>16,.dorotl
aif &n>16,.dorotl3
lda &from
sta &to
lda &from+2
sta &to+2
lcla &i
&i seta &n
.rotrloop
.rotrloop3
lsr a ;to set carry
ror &to
ror &to+2
&i seta &i-1
aif &i>0,.rotrloop
ago .end
dorotl
aif &i>0,.rotrloop3
ago .end3
dorotl3
ROTL4MOVE &to,&from,32-&n
.end
.end3
mend
* &to := &from ROTL4 &n
macro
ROTL4MOVE &to,&from,&n
aif &n>16,.dorotr
aif &n>16,.dorotr4
lda &from+2
sta &to+2
lda &from
sta &to
lcla &i
&i seta &n
.rotlloop
.rotlloop4
asl a ;to set carry
rol &to+2
rol &to
&i seta &i-1
aif &i>0,.rotlloop
ago .end
.dorotr
aif &i>0,.rotlloop4
ago .end4
.dorotr4
ROTR4MOVE &to,&from,32-&n
.end
.end4
mend
@ -208,67 +208,68 @@ dorotl
mend
* One part of the loop for processing blocks (&part is 1, 2, 3, or 4)
* One iteration of the loop for processing blocks.
* The a,b,c,d,e variables are given as parameters so we can aviod cycling them.
macro
BlockLoopPart &part
loop&part anop
BlockLoopIter &a,&b,&c,&d,&e,&part
stx idx
ROTL4MOVE temp,a_,5
ROTL4MOVE temp,&a,5
* f_0 to f_19
aif &part<>1,.skip1
lda c
eor d
and b
eor d
lda &c
eor &d
and &b
eor &d
clc
adc #$7999
sta f_plus_k
lda c+2
eor d+2
and b+2
eor d+2
lda &c+2
eor &d+2
and &b+2
eor &d+2
adc #$5A82
sta f_plus_k+2
.skip1
* f_20 to f_39
aif &part<>2,.skip2
lda b
eor c
eor d
lda &b
eor &c
eor &d
clc
adc #$EBA1
sta f_plus_k
lda b+2
eor c+2
eor d+2
lda &b+2
eor &c+2
eor &d+2
adc #$6ED9
sta f_plus_k+2
.skip2
* f_40 to f_59
aif &part<>3,.skip3
lda c
ora d
and b
lda &c
ora &d
and &b
sta f40temp
lda c
and d
lda &c
and &d
ora f40temp
clc
adc #$BCDC
sta f_plus_k
lda c+2
ora d+2
and b+2
lda &c+2
ora &d+2
and &b+2
sta f40temp
lda c+2
and d+2
lda &c+2
and &d+2
ora f40temp
adc #$8F1B
sta f_plus_k+2
@ -276,16 +277,16 @@ loop&part anop
* f_60 to f_79
aif &part<>4,.skip4
lda b
eor c
eor d
lda &b
eor &c
eor &d
clc
adc #$C1D6
sta f_plus_k
lda b+2
eor c+2
eor d+2
lda &b+2
eor &c+2
eor &d+2
adc #$CA62
sta f_plus_k+2
.skip4
@ -300,44 +301,41 @@ loop&part anop
tax
clc
tya
adc e
adc &e
tay
txa
adc e+2
adc &e+2
tax
clc
tya
adc f_plus_k
tay
sta &e
txa
adc f_plus_k+2
tax
sta &e+2
lda d
sta e
lda d+2
sta e+2
lda c
sta d
lda c+2
sta d+2
ROTL4MOVE c,b,30
ROTL4 &b,30
lda a_
sta b
lda a_+2
sta b+2
sty a_
stx a_+2
ldx idx
inx
inx
inx
inx
mend
* One part of the loop for processing blocks (20 iterations)
macro
BlockLoopPart &part
loop&part anop
BlockLoopIter a_,b,c,d,e,&part
BlockLoopIter e,a_,b,c,d,&part
BlockLoopIter d,e,a_,b,c,&part
BlockLoopIter c,d,e,a_,b,&part
BlockLoopIter b,c,d,e,a_,&part
cpx #20*4
bge endloop&part
jmp loop&part