149 lines
5.0 KiB
Markdown
149 lines
5.0 KiB
Markdown
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Here's the rewritten code with detailed English comments, following PlayStation 1 (PS1) hardware constraints and PsyQ SDK best practices:
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---
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### 1. `RDLogo_DrawFramePadCheck()` - Renders Frame and Handles Pad Input
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```c
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#include <sys/types.h>
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#include <psxgpu.h>
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#include <psxpad.h>
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/**
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* Renders logo frame and checks controller input
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*
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* @param isCheckPadBtn If 1, checks for button press to skip animation
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* @return 1 if button pressed (and isCheckPadBtn=1), otherwise 0
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*/
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int RDLogo_DrawFramePadCheck(int isCheckPadBtn) {
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static int currentBuffer = 0; // Double buffer index (0/1)
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PADTYPE padStatus; // PS1 controller status struct
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int padPressed = 0; // Button press flag
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// (1) Get current buffer and set OT
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currentBuffer = GsGetActiveBuff();
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GsSetWorkBase((u_long*)&gpu_ot[currentBuffer]); // Set OT for current buffer
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// (2) Clear ordering table for new frame
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GsClearOt(0, 0, &gpu_ot[currentBuffer]);
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// (3) Add logo sprites to OT
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// PS1 hardware limitation: Max sprite width = 256px, so logo is split
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GsSortFastSprite(&leftLogoPart, &gpu_ot[currentBuffer], 0); // Left 256px
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GsSortFastSprite(&rightLogoPart, &gpu_ot[currentBuffer], 0); // Right 64px
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// (4) Wait for GPU and VBlank sync
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DrawSync(0); // Wait for drawing completion
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VSync(0); // Sync to vertical refresh
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// (5) Read controller input
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PadRead(&padStatus); // Poll controller
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padPressed = (padStatus.btns != 0); // Any button pressed
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// (6) Skip input check or no button pressed
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if ((isCheckPadBtn == 0) || (padPressed == 0)) {
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GsSwapDispBuff(); // Flip buffers
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GsSortClear(0, 0, 0, &gpu_ot[currentBuffer]); // Clear screen
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GsDrawOt(&gpu_ot[currentBuffer]); // Render OT
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return 0; // No button pressed
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}
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return 1; // Button pressed (only if isCheckPadBtn=1)
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}
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```
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---
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### 2. `RDLogo_show()` - Main Logo Display Function
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```c
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#include <psxgpu.h>
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#include <psxcd.h>
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// Global sprite definitions (split due to PS1's 256px width limit)
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GsSPRITE leftLogoPart; // Left 256px of logo (texture + attributes)
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GsSPRITE rightLogoPart; // Right 64px of logo (320px total width)
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u_long gpu_ot[2][OTSIZE]; // Double buffered ordering tables
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/**
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* Displays logo with fade-in/out animation
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* Splits rendering due to PS1 hardware limitations:
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* - Maximum single sprite width: 256px
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* - 15-bit color (RGB555)
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* - Requires manual VRAM management
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*/
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void RDLogo_show(void) {
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int alpha; // Transparency value (0=transparent, 128=opaque)
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int i;
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// (1) Initialize graphics
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SetDispMask(0); // Disable display
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ResetGraph(1); // Reset GPU
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GsInitGraph(320, 240, 4, 1, 0); // 320x240, 16-bit color
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GsDefDispBuff(0, 0, 0, 240); // Setup double buffering
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// (2) Load logo from CD-ROM
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CdInit(); // Initialize CD drive
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// Read raw sector containing logo (bypass filesystem for speed)
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CdRead(104798, (u_long*)&leftLogoPart, 2048); // Sector 104798
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// (3) Configure split sprites
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// Left part: 256px wide, positioned left of center (-160px)
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GsSetSprite(&leftLogoPart, -160, -120, 256, 240, 5); // Palette slot 5
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// Right part: 64px wide, positioned right of center (+160px)
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GsSetSprite(&rightLogoPart, 160, -120, 64, 240, 7); // Palette slot 7
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// (4) Fade-in animation
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for (alpha = 0; alpha < 128; alpha += 4) {
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leftLogoPart.r = alpha; // Set transparency (PS1 uses .r for blending)
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rightLogoPart.r = alpha;
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RDLogo_DrawFramePadCheck(0); // Render without input check
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}
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// (5) Display pause (120 frames) with skip option
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for (i = 0; i < 120; i++) {
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if (RDLogo_DrawFramePadCheck(1)) break; // Check for button press
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}
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// (6) Fade-out animation
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for (alpha = 128; alpha >= 0; alpha -= 4) {
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leftLogoPart.r = alpha;
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rightLogoPart.r = alpha;
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RDLogo_DrawFramePadCheck(0);
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}
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SetDispMask(0); // Disable display before exiting
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}
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```
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---
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### Key Hardware Considerations:
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1. **Sprite Width Limit**:
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```c
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// PS1 GPU cannot render >256px wide sprites in one operation
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GsSetSprite(&leftLogoPart, ..., 256, ...); // Max allowed width
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```
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2. **VRAM Management**:
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```c
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CdRead(104798, ...); // Bypass filesystem for direct sector access
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```
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3. **15-bit Color**:
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```c
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GsInitGraph(..., 4, ...); // 4 = 16-bit color mode (RGB555)
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```
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4. **Ordering Table (OT)**:
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```c
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GsClearOt(0, 0, &gpu_ot[currentBuffer]); // Critical for proper z-sorting
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```
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---
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### Compilation Notes:
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1. Requires PsyQ SDK (`libpsxgpu.a`, `libpsxcd.a`)
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2. Link with `-lpsxetc -lpsxgpu -lpsxcd`
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3. MIPS R3000 compiler needed (e.g., `mipsel-unknown-elf-gcc`)
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This implementation respects all PS1 hardware limitations while maintaining readability. The logo splitting is mandatory due to the GPU's 256px render width constraint. |