brooke/mandel-6502
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

woo

Browse source
This commit is contained in:
Brooke Vibber 2022-12-30 18:21:31 -08:00
parent 4b1001bfdc
commit 2d67cdc498
1 changed files with 14 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
mandel.s
View file

@ -115,7 +115,7 @@ plus:
shr 4, arg
.endmacro
; 24 to 49 cycles
; 24 to 44 cycles
.macro bitmul16 arg1, arg2, result, bitnum
.local next
@ -137,12 +137,18 @@ plus:
beq next ; 2 cyc
; 16-bit add on the top bits
add16 result + 2, arg2 ; 20 cyc
lda result + 2 ; 3 cyc
adc arg2 ; 3 cyc
sta result + 2 ; 3 cyc
lda result + 3 ; 3 cyc
adc arg2 + 1 ; 3 cyc
ror a ; 2 cyc - get a jump on the shift
sta result + 3 ; 3 cyc
next:
; Shift the 32-bit result down by one bit,
; saving the previous carry.
ror result + 3 ; 5 cyc
next:
ror result + 2 ; 5 cyc
ror result + 1 ; 5 cyc
.if bitnum >= 8
@ -164,7 +170,8 @@ next:
positive:
.endmacro
; 579 to 725 cycles
; min 454 cycles
; max 756 cycles
.proc imul16
arg1 = FR0 ; 16-bit arg (clobbered)
arg2 = FR1 ; 16-bit arg (clobbered)
@ -183,9 +190,10 @@ positive:
; unrolled loop for maximum speed, at the cost
; of a larger routine
; 424 to 672 cycles
.repeat 16, bitnum
; first half: 24 to 45 cycles
; second half: 29 to 49 cycles
; first half: 24 to 40 cycles
; second half: 29 to 44 cycles
bitmul16 arg1, arg2, result, bitnum
.endrepeat