//-------------------------------------------------------------------
//	sisinfo.cpp
//
//	This program reads some SVGA hardware registers and reports 
//	several current display parameters.  (It is specific to the
//	SiS 315 GPU, and is incompatible with other SVGA hardware.)
//
//	programmer: ALLAN CRUSE
//	date begun: 28 JUL 2003
//	completion: 13 OCT 2003
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <unistd.h>	// for gethostname() 
#include <stdlib.h>	// for exit() 
#include <sys/io.h>  	// for iopl() 

#define TSEQ 0x3C4
#define CRTC 0x3D4

int main( int argc, char **argv )
{
	if ( iopl( 3 ) ) { perror( "iopl" ); exit(1); }

	//------------------------------------------
	// report the program-name and machine-name 
	//------------------------------------------	
	char	hostname[ 64 ];
	gethostname( hostname, 63 );
	printf( "\nRunning application \'%s\' ", argv[0] );
	printf( "on workstation \'%s\' \n", hostname );

	//-------------------------------------------------------
	// quick check: exit if non-SiS graphics processor found 
	//-------------------------------------------------------
	outb( 0x05, TSEQ);	// Extended Sequencer Register 5
	short	sr05 = inw( TSEQ );	
	if ( ( sr05 & 0x7FFF ) != 0x2105 ) 
		{
		printf( "\nSiS graphics processor not detected\n\n" );
		exit(1);
		}
	outw( 0x8605, TSEQ );	// unlock SiS Extended Registers	

	//------------------------------------------------------
	// get the current screen-width (horizontal resolution)
	//------------------------------------------------------
	outb( 0x0B, TSEQ );
	short	sr0B = inw( TSEQ );
	outb( 0x01, CRTC );
	short	cr01 = inw( CRTC );
	unsigned long	screen_width = 0;
	screen_width |= ( cr01 >> 8 )&0x0FF;	// bits 7..0
	screen_width |= ( sr0B >> 2 )&0x300;	// bits 9..8
	screen_width += 1;
	screen_width *= 8;

	//-----------------------------------------------------
	// get the current screen-height (vertical resolution)
	//-----------------------------------------------------
	outb( 0x0A, TSEQ );
	short	sr0A = inw( TSEQ );
	outb( 0x07, CRTC );
	short	cr07 = inw( CRTC );
	outb( 0x12, CRTC );
	short	cr12 = inw( CRTC );
	unsigned long	screen_height = 0;
	screen_height |= ( cr12 >> 8 )&0x0FF;	// bits 7..0
	screen_height |= ( cr07 >> 1 )&0x100;	// bit 8
	screen_height |= ( cr07 >> 5 )&0x200;	// bit 9
	screen_height |= ( sr0A << 1 )&0x400;	// bit 10
	screen_height += 1;

	//----------------------------------------------
	// get the current color-depth (bits-per-pixel) 
	//----------------------------------------------
	outb( 0x06, TSEQ );
	short	sr06 = inw( TSEQ );
	unsigned long	color_depth = 0;
	switch( ( sr06 >> 10 )&7 )
		{
		case 0:	color_depth = 8; break;	
		case 1:	color_depth = 15; break;	
		case 2:	color_depth = 16; break;	
		case 4:	color_depth = 24; break;
		}

	//------------------------------------------
	// get the current crt start-address offset
	//------------------------------------------
	outb( 0x0D, CRTC );
	short	cr0D = inw( CRTC );
	outb( 0x0C, CRTC );
	short	cr0C = inw( CRTC );
	outb( 0x0D, TSEQ );
	short	sr0D = inw( TSEQ );
	outb( 0x37, TSEQ );
	short	sr37 = inw( TSEQ );	// NOTE: invalid on SiS 305
	unsigned long	crt_start_address = 0;
	crt_start_address |= ( cr0D >> 8 )&0x000000FF;	// bits 7..0
	crt_start_address |= ( cr0C >> 0 )&0x0000FF00;	// bits 15..8
	crt_start_address |= ( sr0D << 8 )&0x00FF0000;	// bits 23..16
	crt_start_address |= ( sr37 <<16 )&0x03000000;	// bits 25..24
	crt_start_address *= 4;	// TODO: Is this always correct?

	//-----------------------------------------
	// get the current crt line-compare offset
	//-----------------------------------------
	outb( 0x18, CRTC );
	short	cr18 = inw( CRTC );
	outb( 0x09, CRTC );
	short	cr09 = inw( CRTC );
	outb( 0x0F, TSEQ );
	short	sr0F = inw( TSEQ );	
	unsigned long	crt_line_compare = 0;
	crt_line_compare |= ( cr18 >> 8 )&0x00FF;	// bits 7..0
	crt_line_compare |= ( cr07 >> 4 )&0x0100;	// bit 8
	crt_line_compare |= ( cr09 >> 5 )&0x02FF;	// bit 9
	crt_line_compare |= ( sr0F >> 0 )&0x0CFF;	// bits 11..10
	crt_line_compare += 1;

	//------------------------------------------
	// report screen-resolution and pixel-depth
	//------------------------------------------
	printf( "\nscreen-dimensions: " );
	printf( "%d by %d ", screen_width, screen_height );
	if ( sr06 & (1<<9) )
		printf( "\t %d bits-per-pixel ", color_depth );
	else	printf( "\t text mode " );
	printf( "\n" );
	
	//-----------------------------------------
	// report current crt start-address offset
	//-----------------------------------------
	printf( "\ncrt start-address: %d ", crt_start_address );
	printf( "(=0x%08X) ", crt_start_address );

	//----------------------------------------
	// report current crt line_compare offset 
	//----------------------------------------
	printf( "\ncrt line-compare: %d ", crt_line_compare );
	printf( "(=0x%08X) ", crt_line_compare );
	printf( "\n\n" );
}