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Square is a Bad Company (#708)

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* square is a bad company
This commit is contained in:
Revo
2025-05-08 22:26:51 -04:00
committed by GitHub
parent 6d900d30ac
commit 1f9e0d7e6a
2 changed files with 22 additions and 124 deletions
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src/crash_screen.c
+22 -24
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@@ -55,32 +55,33 @@ void crash_screen_draw_glyph(u16* framebuffer, s32 x, s32 y, s32 glyph) {
}
void crash_screen_draw_square(u16* framebuffer);
// Functionally Equivallent.
#ifdef NON_MATCHING
// 0xRGBA (I think A maybe not).
#define WHITE_COLOUR 0xFFFF
#define RED_COLOUR 0xF801
/**
* The big mismatch is the handling of the '6' used in the if statement
* In the target assembly that 6 is saved to 5 different temp registers,
* while in this non-matching decomp its only saved to one temp register.
* This seems to be related to how the innermost for loop is unrolled, but
* its not clear why the target assembley would save the same immediate to
* 5 different registers instead of just re-using one
* There's some stack related differences too, maybe that's related?
**/
void crash_screen_draw_square(u16* framebuffer) {
s32 s0_end;
s32 s2_start;
s32 row;
s32 column;
// (x,y) of top left pixel of square
#define SQUARE_X 40
#define SQUARE_Y 40
for (s2_start = 0x28, s0_end = s2_start + 6; s0_end != 0x2C; s0_end--, s2_start++) {
for (row = s2_start; row < s0_end; row++) {
for (column = s2_start; column < s0_end; column++) {
framebuffer[row * 320 + column] = s0_end - s2_start == 6 ? 0xF801 : 0xFFFF;
#define SQUARE_SIZE_X 6
#define SQUARE_SIZE_Y 6
// width of the square's border being drawn.
#define BORDER_WIDTH 1
#define SQUARE_X2 SQUARE_X + SQUARE_SIZE_Y
#define SQUARE_Y2 SQUARE_Y + SQUARE_SIZE_X
// Here's to you, Yoshimoto, for writing this stupid function. 3 years. 3 years to match.
void crash_screen_draw_square(u16* framebuffer) {
s32 h;
s32 i;
s32 j;
for (h = 0; h < 2; h++) {
for (i = (h * BORDER_WIDTH) + SQUARE_Y; i < (((SQUARE_Y2 - (h * BORDER_WIDTH)))); i++) {
for (j = (h * BORDER_WIDTH) + SQUARE_X; j < (((SQUARE_X2 - (h * BORDER_WIDTH)))); j++) {
framebuffer[(i * 320) + j] = (h == 0) ? (0xF801) : (0xFFFF);
}
}
}
@@ -88,9 +89,6 @@ void crash_screen_draw_square(u16* framebuffer) {
osWritebackDCacheAll();
osViSwapBuffer(framebuffer);
}
#else
GLOBAL_ASM("asm/non_matchings/crash_screen/crash_screen_draw_square.s")
#endif
/**
* Draws three black boxes then prints crash info in the following format: