mirror of https://gitlab.com/camelot/kickc.git
435 lines
8.8 KiB
NASM
435 lines
8.8 KiB
NASM
// 3D Rotation using a Rotation Matrix
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// Based on:
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// - C= Hacking Magazine Issue 8. http://www.ffd2.com/fridge/chacking/c=hacking8.txt
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// - Codebase64 Article http://codebase64.org/doku.php?id=base:3d_rotation
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/// @file
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/// Commodore 64 Registers and Constants
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/// @file
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/// The MOS 6526 Complex Interface Adapter (CIA)
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///
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/// http://archive.6502.org/datasheets/mos_6526_cia_recreated.pdf
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// Commodore 64 PRG executable file
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.file [name="perspective.prg", type="prg", segments="Program"]
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.segmentdef Program [segments="Basic, Code, Data"]
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.segmentdef Basic [start=$0801]
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.segmentdef Code [start=$80d]
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.segmentdef Data [startAfter="Code"]
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.segment Basic
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:BasicUpstart(__start)
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.label print_screen = $400
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// The rotated point - updated by calling rotate()
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.label xr = $a
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.label yr = $b
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.label zr = 8
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// Pointers used to multiply perspective (d/z0-z) onto x- & y-coordinates. Points into mulf_sqr1 / mulf_sqr2.
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.label psp1 = $e
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.label psp2 = $c
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.label print_char_cursor = 2
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.label print_line_cursor = 4
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.segment Code
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__start: {
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// signed char xr
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lda #0
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sta.z xr
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// signed char yr
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sta.z yr
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// signed char zr
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sta.z zr
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// unsigned int psp1
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sta.z psp1
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sta.z psp1+1
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// unsigned int psp2
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sta.z psp2
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sta.z psp2+1
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jsr main
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rts
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}
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main: {
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// asm
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sei
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// mulf_init()
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jsr mulf_init
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// psp1 = (unsigned int)mulf_sqr1
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lda #<mulf_sqr1
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sta.z psp1
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lda #>mulf_sqr1
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sta.z psp1+1
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// psp2 = (unsigned int)mulf_sqr2
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lda #<mulf_sqr2
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sta.z psp2
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lda #>mulf_sqr2
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sta.z psp2+1
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// print_cls()
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jsr print_cls
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// do_perspective($39, -$47, $36)
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jsr do_perspective
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// }
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rts
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}
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// Initialize the mulf_sqr multiplication tables with f(x)=int(x*x) and g(x) = f(1-x)
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mulf_init: {
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.label val = 9
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.label sqr = 4
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.label add = 6
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lda #<1
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sta.z add
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lda #>1
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sta.z add+1
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tay
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sta.z sqr
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sta.z sqr+1
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__b1:
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// char val = BYTE1(sqr)
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lda.z sqr+1
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sta.z val
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// mulf_sqr1[i] = val
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sta mulf_sqr1,y
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// (mulf_sqr1+$100)[i] = val
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sta mulf_sqr1+$100,y
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// -i
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tya
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eor #$ff
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tax
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inx
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// mulf_sqr1[-i] = val
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lda.z val
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sta mulf_sqr1,x
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// (mulf_sqr1+$100)[-i] = val
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sta mulf_sqr1+$100,x
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// mulf_sqr2[i+1] = val
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sta mulf_sqr2+1,y
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// (mulf_sqr2+$100)[i+1] = val
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sta mulf_sqr2+$100+1,y
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// 1-i
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tya
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eor #$ff
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tax
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axs #-1-1
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// mulf_sqr2[1-i] = val
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lda.z val
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sta mulf_sqr2,x
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// (mulf_sqr2+$100)[1-i] = val
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sta mulf_sqr2+$100,x
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// sqr += add
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clc
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lda.z sqr
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adc.z add
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sta.z sqr
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lda.z sqr+1
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adc.z add+1
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sta.z sqr+1
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// add +=2
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lda.z add
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clc
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adc #<2
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sta.z add
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lda.z add+1
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adc #>2
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sta.z add+1
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// for( char i:0..128)
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iny
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cpy #$81
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bne __b1
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// }
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rts
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}
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// Clear the screen. Also resets current line/char cursor.
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print_cls: {
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// memset(print_screen, ' ', 1000)
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jsr memset
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// }
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rts
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}
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// void do_perspective(signed char x, signed char y, signed char z)
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do_perspective: {
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.label x = $39
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.label y = -$47
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.label z = $36
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// print_str("(")
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lda #<print_screen
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sta.z print_char_cursor
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lda #>print_screen
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sta.z print_char_cursor+1
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lda #<str
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sta.z print_str.str
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lda #>str
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sta.z print_str.str+1
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jsr print_str
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// print_schar(x)
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ldx #x
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jsr print_schar
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// print_str(",")
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lda #<str1
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sta.z print_str.str
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lda #>str1
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sta.z print_str.str+1
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jsr print_str
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// print_schar(y)
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ldx #y
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jsr print_schar
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// print_str(",")
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lda #<str1
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sta.z print_str.str
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lda #>str1
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sta.z print_str.str+1
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jsr print_str
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// print_schar(z)
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ldx #z
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jsr print_schar
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// print_str(") -> (")
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lda #<str3
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sta.z print_str.str
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lda #>str3
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sta.z print_str.str+1
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jsr print_str
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// perspective(x, y, z)
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jsr perspective
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// print_uchar((char)xr)
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ldx.z xr
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jsr print_uchar
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// print_str(",")
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lda #<str1
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sta.z print_str.str
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lda #>str1
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sta.z print_str.str+1
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jsr print_str
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// print_uchar((char)yr)
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ldx.z yr
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jsr print_uchar
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// print_str(")")
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lda #<str5
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sta.z print_str.str
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lda #>str5
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sta.z print_str.str+1
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jsr print_str
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// print_ln()
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jsr print_ln
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// }
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rts
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.segment Data
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str: .text "("
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.byte 0
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str1: .text ","
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.byte 0
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str3: .text ") -> ("
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.byte 0
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str5: .text ")"
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.byte 0
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}
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.segment Code
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// Copies the character c (an unsigned char) to the first num characters of the object pointed to by the argument str.
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// void * memset(void *str, char c, unsigned int num)
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memset: {
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.const c = ' '
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.const num = $3e8
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.label str = print_screen
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.label end = str+num
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.label dst = 4
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lda #<str
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sta.z dst
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lda #>str
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sta.z dst+1
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__b1:
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// for(char* dst = str; dst!=end; dst++)
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lda.z dst+1
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cmp #>end
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bne __b2
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lda.z dst
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cmp #<end
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bne __b2
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// }
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rts
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__b2:
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// *dst = c
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lda #c
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ldy #0
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sta (dst),y
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// for(char* dst = str; dst!=end; dst++)
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inc.z dst
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bne !+
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inc.z dst+1
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!:
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jmp __b1
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}
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// Print a zero-terminated string
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// void print_str(__zp(6) char *str)
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print_str: {
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.label str = 6
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__b1:
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// while(*str)
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ldy #0
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lda (str),y
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cmp #0
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bne __b2
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// }
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rts
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__b2:
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// print_char(*(str++))
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ldy #0
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lda (str),y
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jsr print_char
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// print_char(*(str++));
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inc.z str
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bne !+
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inc.z str+1
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!:
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jmp __b1
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}
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// Print a signed char as HEX
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// void print_schar(__register(X) signed char b)
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print_schar: {
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// if(b<0)
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cpx #0
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bmi __b1
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// print_char(' ')
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lda #' '
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jsr print_char
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__b2:
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// print_uchar((char)b)
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jsr print_uchar
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// }
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rts
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__b1:
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// print_char('-')
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lda #'-'
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jsr print_char
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// b = -b
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txa
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eor #$ff
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clc
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adc #1
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tax
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jmp __b2
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}
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// Apply perspective to a 3d-point. Result is returned in (*xr,*yr)
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// Implemented in assembler to utilize seriously fast multiplication
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// void perspective(signed char x, signed char y, signed char z)
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perspective: {
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// xr = x
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lda #do_perspective.x
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sta.z xr
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// yr = y
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lda #do_perspective.y
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sta.z yr
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// zr = z
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lda #do_perspective.z
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sta.z zr
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// asm
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sta PP+1
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PP:
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lda PERSP_Z
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sta psp1
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eor #$ff
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sta psp2
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clc
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ldy yr
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lda (psp1),y
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sbc (psp2),y
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adc #$80
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sta yr
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clc
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ldy xr
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lda (psp1),y
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sbc (psp2),y
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adc #$80
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sta xr
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// }
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rts
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}
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// Print a char as HEX
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// void print_uchar(__register(X) char b)
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print_uchar: {
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// b>>4
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txa
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lsr
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lsr
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lsr
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lsr
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// print_char(print_hextab[b>>4])
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tay
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lda print_hextab,y
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// Table of hexadecimal digits
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jsr print_char
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// b&0xf
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lda #$f
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axs #0
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// print_char(print_hextab[b&0xf])
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lda print_hextab,x
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jsr print_char
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// }
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rts
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}
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// Print a newline
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print_ln: {
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lda #<print_screen
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sta.z print_line_cursor
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lda #>print_screen
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sta.z print_line_cursor+1
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__b1:
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// print_line_cursor + 0x28
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lda #$28
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clc
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adc.z print_line_cursor
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sta.z print_line_cursor
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bcc !+
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inc.z print_line_cursor+1
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!:
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// while (print_line_cursor<print_char_cursor)
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lda.z print_line_cursor+1
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cmp.z print_char_cursor+1
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bcc __b1
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bne !+
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lda.z print_line_cursor
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cmp.z print_char_cursor
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bcc __b1
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!:
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// }
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rts
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}
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// Print a single char
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// void print_char(__register(A) char ch)
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print_char: {
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// *(print_char_cursor++) = ch
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ldy #0
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sta (print_char_cursor),y
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// *(print_char_cursor++) = ch;
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inc.z print_char_cursor
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bne !+
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inc.z print_char_cursor+1
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!:
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// }
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rts
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}
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.segment Data
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print_hextab: .text "0123456789abcdef"
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// Multiplication tables for seriously fast multiplication.
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// This version is optimized for speed over accuracy
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// - It can multiply signed numbers with no extra code - but only for numbers in [-$3f;$3f]
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// - It throws away the low part of the 32-bit result
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// - It return >a*b*4 to maximize precision (when passed maximal input values $3f*$3f the result is $3e)
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// See the following for information about the method
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// - http://codebase64.org/doku.php?id=base:seriously_fast_multiplication
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// - http://codebase64.org/doku.php?id=magazines:chacking16
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// mulf_sqr tables will contain f(x)=int(x*x) and g(x) = f(1-x).
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// f(x) = >(( x * x ))
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.align $100
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mulf_sqr1: .fill $200, 0
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// g(x) = >((( 1 - x ) * ( 1 - x )))
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.align $100
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mulf_sqr2: .fill $200, 0
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// Perspective multiplication table containing (d/(z0-z)[z] for each z-value
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.align $100
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PERSP_Z:
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{
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.var d = 256.0
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.var z0 = 5.0
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.for(var z=0;z<$100;z++) {
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.if(z>127) {
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.byte round(d / (z0 - ((z - 256) / 64.0)));
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} else {
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.byte round(d / (z0 - (z / 64.0)));
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}
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}
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}
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