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51-70 cycles for xe :D

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Brooke Vibber 2024-12-30 15:17:50 -08:00
parent 9b7f6b8937
commit 6db8cef82d
1 changed files with 12 additions and 13 deletions
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25
mandel.s
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@ -463,28 +463,27 @@ bank_switch_table:
.macro imul8 dest, arg1, arg2, xe
.if xe
; using 64KB lookup table
; 53-72 cycles
; 51-70 cycles
; clobbers x, y, dest, ptr
.scope
output = dest
; bottom 14 bits except the LSB are the per-bank table index
; add $4000 for the bank pointer
lda arg1 ; 3 cyc
and #$fe ; 2 cyc
tay ; 2 cyc
lda arg2 ; 3 cyc
and #$3f ; 2 cyc
ora #$40 ; 2 cyc
sta ptr + 1 ; 3 cyc
; top 2 bits are the table bank selector
ldx arg2 ; 3 cyc
lda bank_switch_table,x ; 4 cyc
sta PORTB ; 4 cyc
; bottom 14 bits except the LSB are the per-bank table index
; add $4000 for the bank pointer
txa ; 2 cyc
and #$3f ; 2 cyc
ora #$40 ; 2 cyc
sta ptr + 1 ; 3 cyc
; copy the entry into output
lda arg1 ; 3 cyc
and #$fe ; 2 cyc
tay ; 2 cyc
lda (ptr),y ; 5 cyc
sta output ; 3 cyc
iny ; 2 cyc
@ -503,9 +502,9 @@ bank_switch_table:
and #1 ; 2 cyc
beq done ; 2 cyc
; add the second param one last time for the skipped bit
; add arg2 one last time for the skipped bit
clc ; 2 cyc
lda arg2 ; 3 cyc
txa ; 2 cyc
adc output ; 3 cyc
sta output ; 3 cyc
lda #0 ; 2 cyc