/*
THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.  
COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
*/

#include "pa_enabl.h"                   //$$POLY_ACC
#include "mem.h"

#include "gr.h"
#include "grdef.h"

#if defined(POLY_ACC)
#include "poly_acc.h"
#endif

int Gr_scanline_darkening_level = GR_FADE_LEVELS;

#ifndef MACINTOSH
void gr_linear_darken( ubyte * dest, int darkening_level, int count, ubyte * fade_table );
#pragma aux gr_linear_darken parm [edi] [eax] [ecx] [edx] modify exact [eax ebx ecx edx edi] = \
"					xor	ebx, ebx					"	\
"					mov	bh, al					"  \
"gld_loop:		mov	bl, [edi]				"	\
"					mov	al, [ebx+edx]			"	\
"					mov	[edi], al				"	\
"					inc	edi						"	\
"					dec	ecx						"	\
"					jnz	gld_loop					"
#else
void gr_linear_darken( ubyte * dest, int darkening_level, int count, ubyte * fade_table )
{
	int i;

	for (i=0; i<count; i++ )	{
		*dest = fade_table[*dest+(darkening_level*256)];
		dest++;
	}
}

void gr_linear_stosd( ubyte * dest, ubyte color, unsigned short count )
{
	int i, x;

	if (count > 3) {
		while ((int)(dest) & 0x3) { *dest++ = color; count--; };
		if (count >= 4) {
			x = (color << 24) | (color << 16) | (color << 8) | color;
			while (count > 4) { *(int *)dest = x; dest += 4; count -= 4; };
		}
		while (count > 0) { *dest++ = color; count--; };
	} else {
		for (i=0; i<count; i++ )
			*dest++ = color;
	}
}
#endif

#if defined(POLY_ACC)
//$$ Note that this code WAS a virtual clone of the mac code and any changes to mac should be reflected here.
void gr_linear15_darken( short * dest, int darkening_level, int count, ubyte * fade_table )
{
    //$$ this routine is a prime candidate for using the alpha blender.
    int i;
    unsigned short rt[32], gt[32], bt[32];
    unsigned long level, int_level, dlevel;

    dlevel = (darkening_level << 16) / GR_FADE_LEVELS;
    level = int_level = 0;
    for(i = 0; i != 32; ++i)
    {
        rt[i] = int_level << 10;
        gt[i] = int_level << 5;
        bt[i] = int_level;

        level += dlevel;
        int_level = level >> 16;
    }

    pa_flush();
    for (i=0; i<count; i++ )    {
        if(*dest & 0x8000)
	        *dest =
   	         rt[((*dest >> 10) & 0x1f)] |
      	      gt[((*dest >> 5) & 0x1f)] |
         	   bt[((*dest >> 0) & 0x1f)] |
            	0x8000;
	        dest++;
	}
}

void gr_linear15_stosd( short * dest, ubyte color, unsigned short count )
{
    //$$ this routine is a prime candidate for using the alpha blender.
    short c = pa_clut[color];
    pa_flush();
    while(count--)
        *dest++ = c;
}
#endif

void gr_uscanline( int x1, int x2, int y )
{
	if (Gr_scanline_darkening_level >= GR_FADE_LEVELS )	{
		switch(TYPE)
		{
		case BM_LINEAR:
			gr_linear_stosd( DATA + ROWSIZE*y + x1, COLOR, x2-x1+1);
			break;
		case BM_MODEX:
			gr_modex_uscanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
		case BM_SVGA:
			gr_vesa_scanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
#if defined(POLY_ACC)
        case BM_LINEAR15:
            gr_linear15_stosd( (short *)(DATA + ROWSIZE*y + x1 * PA_BPP), COLOR, x2-x1+1);
			break;
#endif
        }
	} else {
		switch(TYPE)
		{
		case BM_LINEAR:
			gr_linear_darken( DATA + ROWSIZE*y + x1, Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
			break;
		case BM_MODEX:
			gr_modex_uscanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
		case BM_SVGA:
			{
				ubyte * vram = (ubyte *)0xA0000;
				int VideoLocation,page,offset1, offset2;

				VideoLocation = (ROWSIZE * y) + x1;
				page    = VideoLocation >> 16;
				offset1  = VideoLocation & 0xFFFF;
				offset2   = offset1 + (x2-x1+1);

				gr_vesa_setpage( page );
				if ( offset2 <= 0xFFFF )	{
					gr_linear_darken( &vram[offset1], Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
				} else {					 			
					gr_linear_darken( &vram[offset1], Gr_scanline_darkening_level, 0xFFFF-offset1+1, gr_fade_table);
					page++;
					gr_vesa_setpage(page);
					gr_linear_darken( vram, Gr_scanline_darkening_level, offset2 - 0xFFFF, gr_fade_table);
				}
			}
			break;
#if defined(POLY_ACC)
        case BM_LINEAR15:
            gr_linear15_darken( (short *)(DATA + ROWSIZE*y + x1 * PA_BPP), Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
			break;
#endif
        }
	}
}

void gr_scanline( int x1, int x2, int y )
{
	if ((y<0)||(y>MAXY)) return;

	if (x2 < x1 ) x2 ^= x1 ^= x2;

	if (x1 > MAXX) return;
	if (x2 < MINX) return;

	if (x1 < MINX) x1 = MINX;
	if (x2 > MAXX) x2 = MAXX;

	if (Gr_scanline_darkening_level >= GR_FADE_LEVELS )	{
		switch(TYPE)
		{
		case BM_LINEAR:
			gr_linear_stosd( DATA + ROWSIZE*y + x1, COLOR, x2-x1+1);
			break;
		case BM_MODEX:
			gr_modex_uscanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
		case BM_SVGA:
			gr_vesa_scanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
#if defined(POLY_ACC)
        case BM_LINEAR15:
            gr_linear15_stosd( (short *)(DATA + ROWSIZE*y + x1 * PA_BPP), COLOR, x2-x1+1);
			break;
#endif
        }
	} else {
		switch(TYPE)
		{
		case BM_LINEAR:
			gr_linear_darken( DATA + ROWSIZE*y + x1, Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
			break;
		case BM_MODEX:
			gr_modex_uscanline( x1+XOFFSET, x2+XOFFSET, y+YOFFSET, COLOR );
			break;
		case BM_SVGA:
			{
				ubyte * vram = (ubyte *)0xA0000;
				int VideoLocation,page,offset1, offset2;

				VideoLocation = (ROWSIZE * y) + x1;
				page    = VideoLocation >> 16;
				offset1  = VideoLocation & 0xFFFF;
				offset2   = offset1 + (x2-x1+1);

				gr_vesa_setpage( page );
				if ( offset2 <= 0xFFFF )	{
					gr_linear_darken( &vram[offset1], Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
				} else {					 			
					gr_linear_darken( &vram[offset1], Gr_scanline_darkening_level, 0xFFFF-offset1+1, gr_fade_table);
					page++;
					gr_vesa_setpage(page);
					gr_linear_darken( vram, Gr_scanline_darkening_level, offset2 - 0xFFFF, gr_fade_table);
				}
			}
			break;
#if defined(POLY_ACC)
        case BM_LINEAR15:
            gr_linear15_darken( (short *)(DATA + ROWSIZE*y + x1 * PA_BPP), Gr_scanline_darkening_level, x2-x1+1, gr_fade_table);
			break;
#endif
        }
	}
}