PSn00bSDK is an open-source PS1 SDK project that aims to be as close to the official SDK as possible.
PSn00bSDK is a 100% free and open source SDK for developing homebrew games and applications for the original Sony PlayStation. The SDK consists mainly of libraries and some tools for converting and building resources to be used on the console.
While PSn00bSDK is currently a work in progress the project aims to develop an SDK that is as close to the official Sony SDK as possiblein in terms of supported hardware features which include GPU, GTE, SPU, CD, MDEC and controller/memory card peripherals and a library API written to follow the official SDK’s API syntax. With extensive low-level technical documentation of the PSX readily available (such as nocash’s PSX specs) there should be no excuse to not have full support of the aforementioned hardware features.
The PSn00bSDK libraries are written mostly in MIPS assembly language with compiler generated code limited to small and moderately sized support functions for best possible performance and to keep the runtime library footprint as small as possible. Many of the library functions avoid using BIOS calls such as C string and memory manipulation functions and use pure assembly equivalents for improved performance for memory and string manipulation operations.