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PSP's GE is a tile-based deferred renderer similar to PowerVR.
uint8_t *ram = calloc(32, 1024*1024); uint8_t *vram = calloc(4, 1024*1024); uint32_t mem_read32(uint32_t addr) if (addr < 0x02000000) return (uint32_t )(ram + addr); if (addr >= 0x04000000 && addr < 0x04200000) return (uint32_t )(vram + (addr & 0x3FFFFF)); if (addr >= 0x1C000000 && addr < 0x20000000) return hw_read(addr); // handle uncached mirrors (bit 29 cleared) return 0;
PSP games call functions via syscall or direct jump to kernel (0x80000000+). High-Level Emulation (HLE) is preferred for performance. pc psp emulator
void hle_syscall(uint32_t call_id, uint32_t *args) switch(call_id) case 0x1234: // sceDisplaySetFrameBuf g_state.fb_addr = args[0]; g_state.fb_width = args[1]; break; // ... 300+ syscalls
typedef struct uint32_t r[32]; // general purpose regs uint32_t pc; uint32_t hi, lo; // multiply/divide float fpr[32]; // FPU regs uint32_t fcr31; // FPU control // VFPU (vector) – 128 registers float vfpu[128][4]; psp_cpu_t; void cpu_step(psp_cpu_t *cpu) uint32_t instr = mem_read32(cpu->pc); cpu->pc += 4; switch((instr >> 26) & 0x3F) // primary opcode case 0x00: // SPECIAL decode_special(cpu, instr); break; case 0x11: // COP1 (FPU) decode_cop1(cpu, instr); break; case 0x12: // COP2 (VFPU) decode_cop2(cpu, instr); break; // ... other MIPS opcodes PSP's GE is a tile-based deferred renderer similar
This guide focuses on the , core components, and implementation steps. It assumes intermediate knowledge of C/C++, computer architecture, and reverse engineering concepts. Guide: Developing a PSP Emulator for PC 1. Understanding the Target: Sony PSP Hardware | Component | Specification | Emulation Challenge | |-----------|---------------|----------------------| | CPU | MIPS32 R4000 (Allegrex) @ 333 MHz | MIPS interpreter/dynarec, FPU, VFPU (vector unit) | | GPU | "Media Engine" + Rendering Engine @ 166 MHz | OpenGL/Vulkan translation, texture/vertex streaming | | RAM | 32 MB main + 4 MB embedded DRAM (VRAM) | Fast memory mapping, MMU emulation | | Audio | Media Engine + SPU (2 channels, 3D sound) | Buffer mixing, resampling | | Storage | UMD (ISO/CSO), Memory Stick (savedata) | ISO parsing, file system hooks | | OS | ThreadMan, IoFileMgr, PowerCallback, etc. | System call translation | 2. High-Level Emulator Architecture +------------------+ | PSP Game ISO | +------------------+ | v +------------------+ | Loader (PRX/ELF) | +------------------+ | v +------------------+ +------------------+ | CPU Emulation | <-> | Memory Bus | | (Dynarec/Int.) | | (32MB + 4MB) | +------------------+ +------------------+ | | v v +------------------+ +------------------+ | GPU Emulation | | Media Engine | | (OpenGL/Vulkan) | | (Audio/Decode) | +------------------+ +------------------+ | | v v +------------------+ +------------------+ | Host Rendering | | Host Audio API | | (GLFW/SDL2) | | (Pulse/ALSA/XAudio2) +------------------+ +------------------+ 3. Core Components Implementation 3.1 CPU Emulation – MIPS32 + VFPU Option A: Interpreter (simpler, slower)
| Module | Purpose | Example HLE | |--------|---------|--------------| | scePower | CPU clock, standby | Return success, ignore | | sceDisplay | Framebuffer flip | Swap host window buffers | | sceCtrl | Input reading | Read keyboard/gamepad | | sceIo | File I/O | Map to host filesystem | | sceKernel | Threads/semaphores | Map to host threads | | sceAudio | Sound output | Queue to audio callback | standby | Return success
For a faster start, consider contributing to PPSSPP instead of building from scratch – but if your goal is learning, this guide gives you the complete roadmap.