ezfo-disc_io/source/tonccpy.c

#include "tonccpy.h"
//# tonccpy.c

//! VRAM-safe cpy.
/*! This version mimics memcpy in functionality, with 
    the benefit of working for VRAM as well. It is also 
    slightly faster than the original memcpy, but faster 
    implementations can be made.
    \param dst  Destination pointer.
    \param src  Source pointer.
    \param size Fill-length in bytes.
    \note   The pointers and size need not be word-aligned.
*/
void tonccpy(void *dst, const void *src, uint size)
{
    if(size==0 || dst==0 || src==0)
        return;

    uint count;
    u16 *dst16;     // hword destination
    u8  *src8;      // byte source

    // Ideal case: copy by 4x words. Leaves tail for later.
    if( ((u32)src|(u32)dst)%4==0 && size>=4)
    {
        u32 *src32= (u32*)src, *dst32= (u32*)dst;

        count= size/4;
        uint tmp= count&3;
        count /= 4;

        // Duff's Device, good friend!
        switch(tmp) {
            do {    *dst32++ = *src32++;
        case 3:     *dst32++ = *src32++;
        case 2:     *dst32++ = *src32++;
        case 1:     *dst32++ = *src32++;
        case 0:     ; } while(count--);
        }

        // Check for tail
        size &= 3;
        if(size == 0)
            return;

        src8= (u8*)src32;
        dst16= (u16*)dst32;
    }
    else        // Unaligned.
    {
        uint dstOfs= (u32)dst&1;
        src8= (u8*)src;
        dst16= (u16*)(dst-dstOfs);

        // Head: 1 byte.
        if(dstOfs != 0)
        {
            *dst16= (*dst16 & 0xFF) | *src8++<<8;
            dst16++;
            if(--size==0)
                return;
        }
    }

    // Unaligned main: copy by 2x byte.
    count= size/2;
    while(count--)
    {
        *dst16++ = src8[0] | src8[1]<<8;
        src8 += 2;
    }

    // Tail: 1 byte.
    if(size&1)
        *dst16= (*dst16 &~ 0xFF) | *src8;
}
//# toncset.c

//! VRAM-safe memset, internal routine.
/*! This version mimics memset in functionality, with 
    the benefit of working for VRAM as well. It is also 
    slightly faster than the original memset.
    \param dst  Destination pointer.
    \param fill Word to fill with.
    \param size Fill-length in bytes.
    \note   The \a dst pointer and \a size need not be 
        word-aligned. In the case of unaligned fills, \a fill 
        will be masked off to match the situation.
*/
void __toncset(void *dst, u32 fill, uint size)
{
    if(size==0 || dst==0)
        return;

    uint left= (u32)dst&3;
    u32 *dst32= (u32*)(dst-left);
    u32 count, mask;

    // Unaligned head.
    if(left != 0)
    {
        // Adjust for very small stint.
        if(left+size<4)
        {
            mask= BIT_MASK(size*8)<<(left*8);   
            *dst32= (*dst32 &~ mask) | (fill & mask);
            return;
        }

        mask= BIT_MASK(left*8);
        *dst32= (*dst32 & mask) | (fill&~mask);
        dst32++;
        size -= 4-left;
    }

    // Main stint.
    count= size/4;
    uint tmp= count&3;
    count /= 4;

    switch(tmp) {
        do {    *dst32++ = fill;
    case 3:     *dst32++ = fill;
    case 2:     *dst32++ = fill;
    case 1:     *dst32++ = fill;
    case 0:     ; } while(count--);
    }

    // Tail
    size &= 3;
    if(size)
    {
        mask= BIT_MASK(size*8);
        *dst32= (*dst32 &~ mask) | (fill & mask);
    }
}