高速なmemset()/memcpy()のソース

CPP

snesのソースに書いてあったらしい。
なんかに使えるやろ。

# define op_t	unsigned long int
# define OPSIZ	(sizeof(op_t))

void *memset(void *buf, int ch, size_t n)
{
	int		i;

	if (n == 0) return buf;


	if ( ch ){
		for ( i = 0; i < n; i++ ){
			((char*)buf)[i] = ch;
		}
	} else {
		long int dstp = (long int)buf;

		if ( n >= 8 ){
			size_t	xlen;

			while ( (dstp % OPSIZ) != 0 ){
				((char*)dstp)[0] = 0;
				dstp += 1;
				n -= 1;
			}

			xlen = n / (OPSIZ * 8);
			while ( xlen != 0 ){
				((op_t*)dstp)[0] = 0;
				((op_t*)dstp)[1] = 0;
				((op_t*)dstp)[2] = 0;
				((op_t*)dstp)[3] = 0;
				((op_t*)dstp)[4] = 0;
				((op_t*)dstp)[5] = 0;
				((op_t*)dstp)[6] = 0;
				((op_t*)dstp)[7] = 0;
				dstp += 8 * OPSIZ;
				xlen -= 1;
			}
			n %= OPSIZ * 8;

			xlen = n / OPSIZ;
			while ( xlen != 0 ){
				((op_t*)dstp)[0] = 0;
				dstp += OPSIZ;
				xlen -= 1;
			}
			n %= OPSIZ;
		}

		while ( n != 0 ){
			((char*)dstp)[0] = 0;
			dstp += 1;
			n -= 1;
		}
	}

	return buf;
}

void *memcpy(void *dest, const void *src, size_t n)
{
	int		i;

	if (n == 0) return dest;

	for ( i = 0; i < n; i++ ){
		((char*)dest)[i] = ((char*)src)[i];
	}
	return dest;
}