The Comet's Tale ☄️ — Issue #029: Perplexity Labs Ships NES Games, Comet Experiences 6X Query Surge

# Generate the PPU driver - core rendering engine
ppu_driver_c_content = """/*
 * PPU Driver - Graphics Rendering Engine
 * Handles all PPU (Picture Processing Unit) operations
 * Target: NES cc65
 */

#include <nes.h>
#include <string.h>

// OAM buffer (shadow OAM in RAM for DMA transfer)
#define OAM_BUF 0x0200
unsigned char *oam_buffer = (unsigned char*)OAM_BUF;

// Sprite counter for OAM
unsigned char sprite_count = 0;

// Initialize PPU
void ppu_init(void) {
    // Disable rendering
    PPU.control = 0x00;
    PPU.mask = 0x00;
    
    // Clear OAM
    memset(oam_buffer, 0xFF, 256);
    
    // Reset scroll
    PPU.scroll = 0;
    PPU.scroll = 0;
}

// Turn off PPU rendering
void ppu_off(void) {
    PPU.mask = 0x00;
}

// Turn on all PPU rendering
void ppu_on_all(void) {
    PPU.control = 0x90; // Enable NMI, sprites from Pattern Table 0, background from Pattern Table 1
    PPU.mask = 0x1E;    // Enable sprites, background, and left-column rendering
}

// Wait for NMI (v-blank)
void ppu_wait_nmi(void) {
    __asm__("wait_nmi:");
    __asm__("  bit $2002");    // Read PPU status
    __asm__("  bpl wait_nmi"); // Loop until NMI flag is set
}

// Update PPU during v-blank (called from NMI handler)
void ppu_update(void) {
    // Perform OAM DMA transfer
    // This copies 256 bytes from $0200 to OAM
    PPU.oam.dma = 0x02;
    
    // Reset scroll position (for now, fixed at 0,0)
    PPU.scroll = 0;
    PPU.scroll = 0;
}

// Clear OAM buffer
void oam_clear(void) {
    memset(oam_buffer, 0xFF, 256);
    sprite_count = 0;
}

// Add a sprite to OAM buffer
// Returns 1 on success, 0 if OAM is full
unsigned char oam_spr(unsigned char x, unsigned char y, 
                      unsigned char tile, unsigned char attr) {
    if (sprite_count >= 64) {
        return 0; // OAM full
    }
    
    unsigned char offset = sprite_count << 2; // sprite_count * 4
    
    oam_buffer[offset + 0] = y - 1;  // Y position (subtract 1 due to PPU quirk)
    oam_buffer[offset + 1] = tile;   // Tile index
    oam_buffer[offset + 2] = attr;   // Attributes
    oam_buffer[offset + 3] = x;      // X position
    
    sprite_count++;
    return 1;
}

// Add a 16x16 meta-sprite (composed of four 8x8 tiles)
void oam_meta_spr(unsigned char x, unsigned char y, 
                  unsigned char tile, unsigned char attr) {
    // Top-left
    oam_spr(x, y, tile, attr);
    // Top-right
    oam_spr(x + 8, y, tile + 1, attr);
    // Bottom-left
    oam_spr(x, y + 8, tile + 16, attr);
    // Bottom-right
    oam_spr(x + 8, y + 8, tile + 17, attr);
}

// Set palette entry
void pal_col(unsigned char index, unsigned char color) {
    // Set PPU address to palette RAM
    PPU.vram.address = 0x3F;
    PPU.vram.address = index;
    PPU.vram.data = color;
}

// Load a full palette (32 bytes)
void pal_all(const unsigned char *data) {
    unsigned char i;
    
    // Set address to start of palette RAM
    PPU.vram.address = 0x3F;
    PPU.vram.address = 0x00;
    
    // Write all 32 palette bytes
    for (i = 0; i < 32; i++) {
        PPU.vram.data = data[i];
    }
}

// Set background palette (16 bytes)
void pal_bg(const unsigned char *data) {
    unsigned char i;
    
    PPU.vram.address = 0x3F;
    PPU.vram.address = 0x00;
    
    for (i = 0; i < 16; i++) {
        PPU.vram.data = data[i];
    }
}

// Set sprite palette (16 bytes)
void pal_spr(const unsigned char *data) {
    unsigned char i;
    
    PPU.vram.address = 0x3F;
    PPU.vram.address = 0x10;
    
    for (i = 0; i < 16; i++) {
        PPU.vram.data = data[i];
    }
}
"""

with open('/tmp/ppu_driver.c', 'w') as f:
    f.write(ppu_driver_c_content)

print("✓ Generated ppu_driver.c")
print(f"  Size: {len(ppu_driver_c_content)} bytes")