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65
mandel-core.s
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@ -593,57 +593,32 @@ bank_switch_table:
.macro imul8 dest, arg1, arg2, xe
.if xe
; using 64KB lookup table
; 50-55 cycles
; min: 11 + 9 + 9 + 21 = 50
; max: 11 + 9 + 9 + 26 = 55
; 52-69 cycles
; clobbers x, y, dest, ptr
.scope
output = dest
; top 2 bits are the table bank selector
; note we keep arg2 in X after this lookup as we need it later!
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
; note the low byte of ptr is assumed to remain at 0! do not clobber it!
txa ; 2 cyc
and #$3f ; 2 cyc
ora #$40 ; 2 cyc
sta ptr + 1 ; 3 cyc
; mask off the low bit for the index, as the table contains
; entries for every other arg1 value...
lda arg1 ; 3 cyc
tay ; 2 cyc
and #1 ; 2 cyc
bne odd ; 2 cyc
even:
; copy the entry into output
lda arg1 ; 3 cyc
and #$fe ; 2 cyc
tay ; 2 cyc
lda (ptr),y ; 5 cyc
sta output ; 3 cyc
iny ; 2 cyc
lda (ptr),y ; 5 cyc
sta output + 1 ; 3 cyc
jmp done ; 3 cyc
odd:
; skip the LSB for the index
dey ; 2 cyc
; add arg2 one last time for the skipped bit
txa ; 2 cyc
clc ; 2 cyc
adc (ptr), y ; 5 cyc
sta output ; 3 cyc
lda #0 ; 2 cyc
iny ; 2 cyc
adc (ptr),y ; 5 cyc
sta output + 1 ; 3 cyc
sta output+1 ; 3 cyc
; note: we are not restoring memory to save 6 cycles!
; this means those 16kb have to be switched back to base RAM
@ -652,6 +627,18 @@ bank_switch_table:
;;lda #$81 ; 2 cyc - disabled
;;sta PORTB ; 4 cyc - disabled
; check that 1 bit we skipped to fit into space
lda arg1 ; 3 cyc
and #1 ; 2 cyc
beq done ; 2 cyc
; add arg2 one last time for the skipped bit
clc ; 2 cyc
txa ; 2 cyc
adc output ; 3 cyc
sta output ; 3 cyc
add_carry output + 1 ; 2-7 cyc
done:
.endscope
.else
@ -787,8 +774,8 @@ inner_loop:
; min base mem: 81 * 4 + 22 * 2 + 10 + 6 = 384 cyc
; max base mem: 92 * 4 + 27 * 2 + 50 + 6 = 478 cyc
; min ext-mem: 50 * 4 + 22 * 2 + 10 + 6 = 260 cyc
; max ext-mem: 55 * 4 + 27 * 2 + 50 + 6 = 330 cyc
; min ext-mem: 52 * 4 + 22 * 2 + 10 + 6 = 268 cyc
; max ext-mem: 69 * 4 + 27 * 2 + 50 + 6 = 386 cyc
.macro imul16_impl xe
.local arg1
.local arg2
@ -807,18 +794,18 @@ inner_loop:
; h1*h2*256*256 + h1*l2*256 + h2*l1*256 + l1*l2
; l1 * l2
imul8 result, arg1, arg2, xe ; 81-92 or 50-55
imul8 result, arg1, arg2, xe ; 81-92 or 52-69
; 256 * 256 * h1 * h2
imul8 result + 2, arg1 + 1, arg2 + 1, xe ; 81-92 or 50-55
imul8 result + 2, arg1 + 1, arg2 + 1, xe ; 81-92 or 52-69
; 256 * h1 * l1
imul8 inter, arg1 + 1, arg2, xe ; 81-92 or 50-55
imul8 inter, arg1 + 1, arg2, xe ; 81-92 or 52-69
add16 result + 1, result + 1, inter ; 20 cyc
add_carry result + 3 ; 2-7 cyc
; 256 * l1 * h2
imul8 inter, arg1, arg2 + 1, xe ; 81-92 or 50-55
imul8 inter, arg1, arg2 + 1, xe ; 81-92 or 52-69
add16 result + 1, result + 1, inter ; 20 cyc
add_carry result + 3 ; 2-7 cyc
@ -839,8 +826,8 @@ arg2_pos:
; min base ram: 5 + 19 * 2 + 81 + 22 * 2 + 6 = 174
; max base ram: 23 + 19 * 2 + 92 + 27 * 2 + 6 = 213
; min ext ram: 5 + 19 * 2 + 50 + 22 * 2 + 6 = 143
; max ext ram: 23 + 19 * 2 + 55 + 27 * 2 + 6 = 176
; min ext ram: 5 + 19 * 2 + 52 + 22 * 2 + 6 = 145
; max ext ram: 23 + 19 * 2 + 69 + 27 * 2 + 6 = 190
.macro sqr16_impl xe
.scope
arg = FR0 ; 16-bit arg (clobbered)
@ -866,7 +853,7 @@ arg2_pos:
sqr8 result + 2, arg + 1 ; 19 cyc
; 2 * h * l * 256
imul8 inter, arg + 1, arg, xe ; 81-92 / 50-55 cyc
imul8 inter, arg + 1, arg, xe ; 81-92 / 52-69 cyc
add16 result + 1, result + 1, inter ; 20 cyc
add_carry result + 3 ; 2-7 cyc
add16 result + 1, result + 1, inter ; 20 cyc