memset_n.h

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/*
Copyright (C) 2002-2004 The Pentagram Team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/

//
// memset_n is a set of optimized functions for filling buffers of 
// 16 and 32 bit integers
// 

#ifndef MEMSET_N_H_INCLUDED
#define MEMSET_N_H_INCLUDED

namespace Pentagram {

#if defined(__GNUC__) && defined(i386)

//
// GNU i386 memset_32
//
// asm version for the memset32 for gcc/x86
//
// borrowed from SDL's src/video/SDL_memops.h (SDL_memset4)
//
// buf should be DWORD aligned
//
inline void memset_32_aligned(void *buf, uint32 val, uint32 dwords)
{
        int u0, u1, u2;
    __asm__ __volatile__ (                                  \
                        "cld\n\t"                                       \
            "rep ; stosl\n\t"                               \
            : "=&D" (u0), "=&a" (u1), "=&c" (u2)            \
            : "0" (buf), "1" (val), "2" (dwords)            \
            : "memory" );
}

#elif defined(_MSC_VER) && defined(_M_IX86) && (_M_IX86 >= 300)

#ifdef USE_MMX_ASM      // Disabled by default, no obvious speed up

//
// MSVC MMX memset_32
//
// asm version for the memset32 for MSVC MMX x86 
//
// buf should be DWORD aligned
//
inline void memset_32_aligned(void *buf, uint32 val, uint32 dwords)
{
        // Qword align
        if ((uint32)(buf) & 4) 
        {
                *(reinterpret_cast<uint32*>(buf)) = val;
                buf = (reinterpret_cast<uint32*>(buf))+1;
                dwords--;
        }

        if (dwords > 1) 
        {
                __asm {
                        cld
                        mov   edi,  buf
                        mov   ecx,  dwords
                        shr       ecx,  1
                        mov   eax,  val
                        movd  mm0,  eax
                        movd  mm1,  eax
                        psllq mm1,  32
                        por   mm0,  mm1
                        align 16
        repeat:
                        movq [edi], mm0
                        add   edi,  8
                        loop  repeat
                        emms
                };
        }

        // Final dword
        if (dwords & 1) *(reinterpret_cast<uint32*>(buf)) = val;
}

#else // USE_MMX_ASM

//
// MSVC i386 memset_32
//
// asm version for the memset32 for MSVC x86 
//
// buf should be DWORD aligned
//
inline void memset_32_aligned(void *buf, uint32 val, uint32 dwords)
{
        __asm {
                cld
                mov edi, buf
                mov eax, val
                mov ecx, dwords
                repne stosd
        };
}

#endif // USE_MMX_ASM

#else

//
// Generic memset_32
//
// Can be used by all
//
inline void memset_32_aligned(void *buf, uint32 val, uint32 dwords)
{
        do
        { 
                *reinterpret_cast<uint32*>(buf) = val; 
                buf = (reinterpret_cast<uint32*>(buf))+1;
        } 
        while (--dwords);
}

#endif

//
// memset_32
//
// Can be used by all
//
inline void memset_32(void *buf, uint32 val, uint32 dwords)
{
        // Fisrly we should dword Align it
        int align = 0;
        if (reinterpret_cast<uintptr>(buf) & 3) 
        {
                align = 4;
                dwords--;

                // Ok, shift along by 1 byte
                if ((reinterpret_cast<uintptr>(buf) & 1))
                {
                        *reinterpret_cast<uint8*>(buf) = static_cast<uint8>(val&0xFF); 
                        buf = (reinterpret_cast<uint8*>(buf))+1;
                        val = ((val& 0xFF) << 24) || ((val& 0xFFFFFF00) >> 8);
                        align --;
                }

                // Ok, shift along by 2 bytes
                if ((reinterpret_cast<uintptr>(buf) & 2))
                {
                        *reinterpret_cast<uint16*>(buf) = static_cast<uint16>(val&0xFFFF); 
                        buf = (reinterpret_cast<uint16*>(buf))+1;
                        val = ((val& 0xFFFF) << 16) || ((val& 0xFFFF0000) >> 16);
                        align-=2;
                }
        }

        // Fill Aligned
        memset_32_aligned(buf,val,dwords);

        // Do the unaligned data
        if (align)
        {
                // Ok, shift along by 1 byte
                if (align == 1)
                {
                        *reinterpret_cast<uint8*>(buf) = static_cast<uint8>(val&0xFF); 
                }
                // Ok, shift along by 2 bytes
                else
                {
                        *reinterpret_cast<uint16*>(buf) = static_cast<uint16>(val&0xFFFF); 

                        // Ok, shift along by another byte
                        if (align & 1) *(reinterpret_cast<uint8*>(buf)+2) = static_cast<uint8>((val>>16)&0xFF); 
                }
        }
}

//
// memset_16
//
// Can be used by all
//
inline void memset_16(void *buf, sint32 val, uint32 words)
{
        // Use memset_32
        if (words > 1) memset_32(buf,val|val<<16,words>>1);

        // Final word
        if (words & 1) *(reinterpret_cast<uint16*>(buf)) = static_cast<uint16>(val&0xFFFF);
}

}

#endif //MEMSET_N_H_INCLUDED

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