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corrupt! but it produces pixels

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Brooke Vibber 2023-01-22 10:42:37 -08:00
parent b4721ae46b
commit ae9dd0674d
1 changed files with 27 additions and 37 deletions
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64
mandel.s
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@ -168,7 +168,7 @@ color_map:
.endmacro .endmacro
.macro add32 dest, arg1, arg2 .macro add32 dest, arg1, arg2
add 2, dest, arg2, dest add 4, dest, arg2, dest
.endmacro .endmacro
; 2 + 9 * byte cycles ; 2 + 9 * byte cycles
@ -422,6 +422,13 @@ next:
.endmacro .endmacro
.macro shift_round_16 arg, shift
.repeat shift
shl32 arg
.endrepeat
round16 arg
.endmacro
.proc mandelbrot .proc mandelbrot
; input: ; input:
; cx: position scaled to 4.12 fixed point - -8..+7.9 ; cx: position scaled to 4.12 fixed point - -8..+7.9
@ -445,64 +452,48 @@ initloop:
bne initloop bne initloop
loop: loop:
; 1939 - 3007 cyc ; iter++ & max-iters break
inc iter
; iter++ & max-iters break = 7 cyc bne keep_going
inc iter ; 5 cyc
bne keep_going ; 2 cyc
rts rts
keep_going: keep_going:
; 4.12: (-8 .. +7.9) ; 4.12: (-8 .. +7.9)
; zx = zx_2 - zy_2 + cx = 3 * 20 = 60 cyc ; zx = zx_2 - zy_2 + cx
sub16 zx, zx_2, zy_2 sub16 zx, zx_2 + 2, zy_2 + 2
add16 zx, zx, cx add16 zx, zx, cx
; zy = zx_zy + zx_zy + cy = 3 * 20 = 60 cyc ; zy = zx_zy + zx_zy + cy
sub16 zy, zx_zy, zx_zy add16 zy, zx_zy + 2, zx_zy + 2
add16 zy, zy, cy add16 zy, zy, cy
; 8.24: (-128 .. +127.9) ; 8.24: (-128 .. +127.9)
; zx_2 = zx * zx = 518 - 828 cyc ; zx_2 = zx * zx
imul16 zx_2, zx, zx imul16 zx_2, zx, zx
; zy_2 = zy * zy = 518 - 828 cyc ; zy_2 = zy * zy
imul16 zy_2, zy, zy imul16 zy_2, zy, zy
; zx_zy = zx * zy = 518 - 828 cyc ; zx_zy = zx * zy
imul16 zx_zy, zx, zy imul16 zx_zy, zx, zy
; dist = zx_2 + zy_2 = 38 cyc ; dist = zx_2 + zy_2
add32 dist, zx_2, zy_2 add32 dist, zx_2, zy_2
; if dist >= 4 break, else continue iterating = 7 cyc ; if dist >= 4 break, else continue iterating
lda dist + 3 ; 3 cyc lda dist + 3
cmp #4 ; 2 cyc cmp #4
bmi still_in ; 2 cyc bmi still_in
rts rts
still_in: still_in:
; shift and round zx_2 to 4.12 = (60 + 5) - (60 + 28) = 65 - 88 cyc shift_round_16 zx_2, 4
.repeat 4 ; 60 cyc shift_round_16 zy_2, 4
shl24 zx_2 ; 15 cyc shift_round_16 zx_zy, 4
.endrepeat
round16 zx_2 ; 5-28 cycles
; shift and round zy_2 to 4.12 = (20 + 5) - (20 + 28) = 65 - 88 cyc
.repeat 4 ; 60 cyc
shl24 zy_2 ; 15 cyc
.endrepeat
round16 zy_2 ; 5-28 cycles
; shift and round zx_zy to 4.12 = (20 + 5) - (20 + 28) = 65 - 88 cyc
.repeat 4 ; 60 cyc
shl24 zx_zy ; 15 cyc
.endrepeat
round16 zx_zy ; 5-28 cycles
; if may be in the lake, look for looping output with a small buffer ; if may be in the lake, look for looping output with a small buffer
; as an optimization vs running to max iters ; as an optimization vs running to max iters
jmp loop ; 3 cycles jmp loop
.endproc .endproc
@ -708,7 +699,6 @@ loop_sx:
zoom_factor cx, sx, zoom, aspect_x zoom_factor cx, sx, zoom, aspect_x
zoom_factor cy, sy, zoom, aspect_y zoom_factor cy, sy, zoom, aspect_y
jsr mandelbrot jsr mandelbrot
inc iter
jsr pset jsr pset
clc clc