//
//
// Faster versions of common routines
//
//
//---------------------------------------------------------------------------//
// Copyright (C) Microsoft Corporation. All rights reserved.                 //
//===========================================================================//

#include <gameos.hpp>
#include <stdlib.h>

void memclear(void *Dest,int Length);
void memfill(void *Dest,int Length);







extern enum { CPU_UNKNOWN, CPU_PENTIUM, CPU_MMX, CPU_KATMAI } Processor;
static _int64 fillnum=-1;


//
// Instead of using memset(x,0,x) - use this function
//
void memclear(void *Dest,int Len)
{
	_asm{

		mov edi,Dest
		mov ecx,Len
		cmp Processor,CPU_MMX
		jnz mem1

//memclear_mmx:
		mov ebx,ecx				; 8 byte align edi when possible
		sub ecx,edi
		xor eax,eax
		sub ecx,ebx
		and ecx,7
		sub ebx,ecx
		jle doalign0
		test ecx,ecx
		jz mmx0a
mmx0:	mov byte ptr [edi],al
		inc edi
		dec ecx
		jnz mmx0
mmx0a:	mov ecx,ebx
		and ebx,7
		shr ecx,3
		jz doalign0
		pxor mm0,mm0
mmx1:	movq [edi],mm0
		add edi,8
		dec ecx
		jnz mmx1
doalign0:
		add ecx,ebx
		test ecx,ecx
		jz mmx0d
mmx0c:	mov byte ptr [edi],al
		inc edi
		dec ecx
		jnz mmx0c

mmx0d:	emms
		jmp done

mem1:
		mov ebx,ecx				; DWORD align edi when possible
		sub ecx,edi
		xor eax,eax
		sub ecx,ebx
		and ecx,3
		sub ebx,ecx
		jle doalign1
		rep stosb
		mov ecx,ebx
		and ebx,3
		shr ecx,2
		rep stosd
doalign1:
		add ecx,ebx
		rep stosb
done:
		}
};





//
// Instead of using memset(x,0xff,x) - use this function
//
void memfill(void *Dest,int Len)
{
	_asm{

		mov edi,Dest
		mov ecx,Len
		cmp Processor,CPU_MMX
		jnz memf1

//memfill_mmx:
		mov ebx,ecx				; 8 byte align edi when possible
		sub ecx,edi
		mov eax,-1
		sub ecx,ebx
		and ecx,7
		sub ebx,ecx
		jle doalign0
		test ecx,ecx
		jz mmx0fa
mmx0f:	mov byte ptr [edi],al
		inc edi
		dec ecx
		jnz mmx0f
mmx0fa:	mov ecx,ebx
		and ebx,7
		shr ecx,3
		jz doalign0
		movq mm0,fillnum
mmx1:	movq [edi],mm0
		add edi,8
		dec ecx
		jnz mmx1
doalign0:
		add ecx,ebx
		test ecx,ecx
		jz mmx0fb
mmx1f:	mov byte ptr [edi],al
		inc edi
		dec ecx
		jnz mmx1f
mmx0fb:
		emms
		jmp done

memf1:
		mov ebx,ecx				; DWORD align edi when possible
		sub ecx,edi
		mov eax,-1
		sub ecx,ebx
		and ecx,3
		sub ebx,ecx
		jle doalign1
		rep stosb
		mov ecx,ebx
		and ebx,3
		shr ecx,2
		rep stosd
doalign1:
		add ecx,ebx
		rep stosb
done:
		}
};

//---------------------------------------------------------------------------
// Random Number Functions
long RandomNumber (long range)
{
	gosASSERT( RAND_MAX==(1<<15)-1 );		// This is always TRUE in VC

	return( (gos_rand()*range)>>15 );			// Used to used mod (%) - which costs 40+ cycles (AG)
}

//---------------------------------------------------------------------------
bool RollDice (long percent)
{
	return (((rand()*100)>>15) < percent);			// Optimized the % out
}