libfastmem

Very optimized set of memory manipulation functions for the Sega Dreamcast.

Introduction

libfastmem is a tiny library for KallistiOS that provides set of functions dedicated to memory manipulation, that are very optimized in terms of speed and/or memory. These functions can be used in remplacement of standard functions provided by Newlib, but keep in mind that all functions provided in that library are suffixed with the _fast prefix.

This library is intended to be used as a KallistiOS Port (kos-ports) but it can be used as a KallistiOS add-on as well.

Available functions

You need to include <fastmem/fastmem.h> in your project.

This library ship 3 functions:

• memset_fast
• memcpy_fast
• memmove_fast

memset_fast

Set an area of memory.

void *memset_fast(void *s, int c, size_t n);

This function converts the argument c into an unsigned char and fills the first n characters of the array pointed to by s to the value.

memcpy_fast

Copy memory regions.

void *memcpy_fast(void *dst, const void *src, size_t n);

This function copies n bytes from the memory region pointed to by src to the memory region pointed to by dst. It is assumed that there is no overlap between src and dst. If there is an overlap, then the results are undefined.

memmove_fast

Copy memory area.

void *memmove_fast(void *dst, const void *src, size_t n);

This function copies n bytes from memory area src to memory area dst. The memory areas may overlap: copying takes place as though the bytes in src are first copied into a temporary array that does not overlap src or dst, and the bytes are then copied from the temporary array to dst.

Installation

This library can be installed using 2 ways:

1. Using the libfastmem KallistiOS Ports (in kos-ports)
2. Cloning this repository directly in your ${KOS_BASE}/addons directory. In that case you just have to enter this directory and build the library with make.

Credits

memset_fast

Copyright (C) 1999 Niibe Yutaka

Copyright (c) 2009 STMicroelectronics Ltd

Optimized using 64bit data transfer (via FPU) and the movca.l inst, by Giuseppe Cavallaro

memcpy_fast

Copyright (C) 1999 Niibe Yutaka

Copyright (c) 2002 STMicroelectronics Ltd

Modified from memcpy.S and micro-optimized for SH4, by Stuart Menefy

Copyright (c) 2009 STMicroelectronics Ltd

Optimized using prefetching and 64bit data transfer via FPU, by Giuseppe Cavallaro

memmove_fast

Copyright (C) 1999 Niibe Yutaka

About

These functions were intended to be directly merged in KallistiOS patches but unfortunately, this couldn't be done due to licensing issue. These functions remain very interesting for Sega Dreamcast programming, that's why these were published in that library.