Crate psx_gte 

GTE (COP2) access – PS1 Geometry Transformation Engine.

The GTE isn’t memory-mapped. It’s MIPS coprocessor 2, accessed via a dedicated instruction class (MTC2/MFC2/CTC2/CFC2 to move data between CPU and COP2 registers, COP2 cofun to run function ops like RTPS/RTPT/MVMVA/NCDS).

This crate exposes two layers:

• Low-level register macros: write_data!, read_data!, write_control!, read_control!. Each takes a literal register index (0..31) so the assembler emits the correct immediate field. Use these when you need direct access for performance-sensitive paths.

• High-level operation wrappers: zero-argument inline functions for the common GTE commands with their typical options baked in (e.g. ops::project_single uses sf=1, lm=0). On MIPS each compiles to a single 4-byte .word. On host they dispatch to a per-thread software GTE living in host.

All function-op wrappers are unsafe fn – they assume the caller has loaded the required input registers via the register macros.

Same simulation, two backends

• On target_arch = "mips" everything compiles down to direct coprocessor instructions, identical to writing the assembly by hand.
• On host the macros and ops route through psx_gte_core::Gte stored in a thread_local! cell. The simulation is the bit-faithful one the emulator already runs against PCSX-Redux’s parity oracle, so editor previews match what the hardware draws.

Example

use psx_gte::{ops::project_single, read_data, write_control, write_data};

unsafe {
    write_control!(0, 0x0000_1000); // RT[0][0]=0x1000, RT[0][1]=0
    // … fill in the rest of the rotation matrix and TR …
    write_data!(0, (10 & 0xFFFF) | (20 << 16));
    write_data!(1, 30);
    project_single();
    let sxy2: u32 = read_data!(14);
}

Modules

encoding

The COP2 instruction encodings the wrappers emit (psx_hw::gte). GTE (COP2) instruction encodings.

host

Host-side GTE shim.

lighting

Up-to-3-directional-light rig, rendered via the GTE’s hardware lighting pipeline (NCCS / NCDS / NCS ops).

math

Fixed-point math types for GTE inputs/outputs.

ops

GTE function-op wrappers.

regs

GTE register accessors.

scene

Scene / camera / projection helpers.

transform

Composable 3D transform math.

Macros

mfc2Deprecated

Renamed to read_data!.

mtc2Deprecated

Renamed to write_data!.

read_control

Read a GTE control register (CFC2). Same load-delay concern as read_data! – emits a NOP after the CFC2 to give the result a cycle to commit to $8 before Rust’s compiler-inserted move-from-$8 runs.

read_data

Read a GTE data register (MFC2). Expands to a single MFC2 instruction with the register index baked into the .word encoding, followed by a NOP that fills the one-cycle load-delay slot.

write_control

Write a GTE control register (CTC2).

write_data

Write a GTE data register (MTC2). Expands to a single MTC2 instruction.