screen_savers/Nebula: Convert draw_stars.S to C.
Hand-translated. I left the assembly in as comments for easy analysis, I'll remove it in the next commit.
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Augustin Cavalier
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c93cc19069
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413d14fb36
110
src/add-ons/screen_savers/nebula/DrawStars.c
Normal file
110
src/add-ons/screen_savers/nebula/DrawStars.c
Normal file
@ -0,0 +1,110 @@
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// Hand-translated from x86 assembly.
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/* this function needs a definition from outside (the width of the bitmap) */
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// #define STAR_WIDTH 320
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// #define STAR_FUNCTION draw_stars320
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/* draw a star (5 pixels) */
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void STAR_FUNCTION(char* dstParam, char incParam)
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{
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// movl 8(%ebp),%edi /* dst */
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// movl 12(%ebp),%edx /* inc */
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//
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unsigned char* dst;
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unsigned char inc;
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dst = (unsigned char*)dstParam;
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inc = (unsigned char)incParam;
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dst[STAR_WIDTH] += inc;
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if (dst[STAR_WIDTH] < inc) {
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// addb %dl,(STAR_WIDTH)(%edi)
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// Overflowed.
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dst[STAR_WIDTH] = 255;
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// movb $255,(STAR_WIDTH)(%edi)
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}
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// jnc 3f
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//
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//3:
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inc >>= 1;
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// shrb $1,%dl
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unsigned char al;
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al = *dst;
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// movb (%edi),%al
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unsigned char cl;
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cl = dst[STAR_WIDTH - 1];
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// movb (STAR_WIDTH-1)(%edi),%cl
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al += inc;
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// addb %dl,%al
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if (al >= inc) {
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cl += inc;
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// addb %dl,%cl
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if (cl < inc) {
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// jc 2f
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// 2:
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*dst = 255;
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// movb $255,(%edi)
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dst[STAR_WIDTH - 1] = 255;
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// movb $255,(STAR_WIDTH-1)(%edi)
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} else {
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*dst = al;
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// movb %al,(%edi)
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dst[STAR_WIDTH - 1] = cl;
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// movb %cl,(STAR_WIDTH-1)(%edi)
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}
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} else {
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// 1:
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cl += inc;
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// addb %dl,%cl
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if (cl < inc) {
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// jc 2f
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*dst = 255;
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// movb $255,(%edi)
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dst[STAR_WIDTH - 1] = 255;
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// movb $255,(STAR_WIDTH-1)(%edi)
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} else {
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*dst = 255;
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// movb $255,(%edi)
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dst[STAR_WIDTH - 1] = cl;
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// movb %cl,(STAR_WIDTH-1)(%edi)
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}
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}
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al = dst[STAR_WIDTH * 2];
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// movb 2*STAR_WIDTH(%edi),%al
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cl = dst[STAR_WIDTH + 1];
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// movb (STAR_WIDTH+1)(%edi),%cl
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al += inc;
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// addb %dl,%al
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if (al < inc) {
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// jc 11f
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cl += inc;
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// addb %dl,%cl
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if (cl >= inc) {
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dst[STAR_WIDTH * 2] = 255;
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// movb $255,(2*STAR_WIDTH)(%edi)
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dst[STAR_WIDTH + 1] = cl;
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// movb %cl,(STAR_WIDTH+1)(%edi)
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return;
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}
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} else {
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cl += inc;
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// addb %dl,%cl
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if (cl >= inc) {
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// jc 21f
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dst[STAR_WIDTH * 2] = al;
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// movb %al,2*STAR_WIDTH(%edi)
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dst[STAR_WIDTH + 1] = cl;
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// movb %cl,(STAR_WIDTH+1)(%edi)
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return;
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}
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}
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//
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//21:
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dst[STAR_WIDTH * 2] = 255;
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// movb $255,2*STAR_WIDTH(%edi)
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dst[STAR_WIDTH + 1] = 255;
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// movb $255,(STAR_WIDTH+1)(%edi)
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// popl %edi
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// leave
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// ret
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}
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@ -33,18 +33,38 @@ float presin[512];
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typedef unsigned short word;
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extern "C" {
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#include "Draw.c"
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#include "Draw.c"
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void draw_stars320(char *, char);
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void draw_stars512(char *, char);
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void draw_stars576(char *, char);
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void draw_stars640(char *, char);
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void draw_stars800(char *, char);
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void draw_stars1024(char *, char);
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void draw_stars1152(char *, char);
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void draw_stars1280(char *, char);
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void draw_stars1400(char *, char);
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void draw_stars1600(char *, char);
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#define STAR_WIDTH 320
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#define STAR_FUNCTION draw_stars320
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#include "DrawStars.c"
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#define STAR_WIDTH 512
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#define STAR_FUNCTION draw_stars512
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#include "DrawStars.c"
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#define STAR_WIDTH 576
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#define STAR_FUNCTION draw_stars576
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#include "DrawStars.c"
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#define STAR_WIDTH 640
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#define STAR_FUNCTION draw_stars640
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#include "DrawStars.c"
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#define STAR_WIDTH 800
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#define STAR_FUNCTION draw_stars800
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#include "DrawStars.c"
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#define STAR_WIDTH 1024
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#define STAR_FUNCTION draw_stars1024
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#include "DrawStars.c"
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#define STAR_WIDTH 1152
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#define STAR_FUNCTION draw_stars1152
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#include "DrawStars.c"
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#define STAR_WIDTH 1280
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#define STAR_FUNCTION draw_stars1280
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#include "DrawStars.c"
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#define STAR_WIDTH 1400
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#define STAR_FUNCTION draw_stars1400
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#include "DrawStars.c"
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#define STAR_WIDTH 1600
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#define STAR_FUNCTION draw_stars1600
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#include "DrawStars.c"
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}
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const uint32 kMsgWidth = 'widt';
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@ -1,78 +0,0 @@
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.text
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/* this function needs a definition from outside (the width of the bitmap) */
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// #define STAR_WIDTH 320
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// #define STAR_FUNCTION draw_stars320
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/* draw a star (5 pixels) */
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.globl STAR_FUNCTION
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.type STAR_FUNCTION,@function
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STAR_FUNCTION:
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pushl %ebp
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movl %esp,%ebp
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pushl %edi
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movl 8(%ebp),%edi /* dst */
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movl 12(%ebp),%edx /* inc */
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addb %dl,(STAR_WIDTH)(%edi)
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jnc 3f
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movb $255,(STAR_WIDTH)(%edi)
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3:
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shrb $1,%dl
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movb (%edi),%al
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movb (STAR_WIDTH-1)(%edi),%cl
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addb %dl,%al
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jc 1f
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addb %dl,%cl
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jc 2f
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movb %al,(%edi)
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movb %cl,(STAR_WIDTH-1)(%edi)
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jmp 31f
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1:
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addb %dl,%cl
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jc 2f
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movb $255,(%edi)
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movb %cl,(STAR_WIDTH-1)(%edi)
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jmp 31f
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2:
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movb $255,(%edi)
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movb $255,(STAR_WIDTH-1)(%edi)
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31:
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movb 2*STAR_WIDTH(%edi),%al
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movb (STAR_WIDTH+1)(%edi),%cl
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addb %dl,%al
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jc 11f
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addb %dl,%cl
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jc 21f
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movb %al,2*STAR_WIDTH(%edi)
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movb %cl,(STAR_WIDTH+1)(%edi)
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popl %edi
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leave
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ret
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11:
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addb %dl,%cl
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jc 21f
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movb $255,(2*STAR_WIDTH)(%edi)
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movb %cl,(STAR_WIDTH+1)(%edi)
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popl %edi
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leave
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ret
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21:
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movb $255,2*STAR_WIDTH(%edi)
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movb $255,(STAR_WIDTH+1)(%edi)
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popl %edi
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leave
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ret
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@ -7,8 +7,6 @@ LIBS = -lbe -lscreensaver
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NAME = Nebula
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FILES = Nebula
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ASMFILES =
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STARFILE = draw_stars
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STARWIDTHS = 320 512 576 640 800 1024 1152 1280 1400 1600
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OBJDIR = obj.x86
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STARFILES := $(foreach f, $(STARWIDTHS), $(STARFILE)$(f))
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@ -38,11 +36,5 @@ Nebula: $(OBJS)
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$(OBJDIR)/%.o : %.cpp
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$(CC) -c $*.cpp -o $(OBJDIR)/$*.o $(CFLAGS)
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$(OBJDIR)/$(STARFILE)%.o : $(STARFILE).S
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$(CC) -c $(STARFILE).S -DSTAR_WIDTH=$* -DSTAR_FUNCTION=draw_stars$* -o $@
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$(OBJDIR)/%.o : %.S
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$(CC) -c $*.S -o $(OBJDIR)/$*.o $(CFLAGS)
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tar zip backup:
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@zip `basename $(NAME)`-`date +%Y-%m-%d`.zip *.[chS]* *.rsrc makefile
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