atari_ntsc.h

/* Atari GTIA NTSC composite video to RGB emulator/blitter */

#ifndef ATARI_NTSC_H
#define ATARI_NTSC_H

/* Picture parameters, ranging from -1.0 to 1.0 where 0.0 is normal. To easily
clear all fields, make it a static object then set whatever fields you want:
	static snes_ntsc_setup_t setup;
	setup.hue = ... */
typedef struct atari_ntsc_setup_t
{
	float hue;
	float saturation;
	float contrast;
	float brightness;
	float sharpness;
	float burst_phase; /* not in radians; -1.0 = -180 degrees, 1.0 = +180 degrees */
	float gaussian_factor;
	/* gamma adjustment */
	float gamma_adj;
	/* lower saturation for higher luma values */
	float saturation_ramp;
} atari_ntsc_setup_t;

/* private */
enum { atari_ntsc_entry_size = 56 };
enum { atari_ntsc_color_count = 256 };
typedef unsigned long ntsc_rgb_t;
/*end private*/

/* Caller must allocate space for blitter data, which uses 56 KB of memory. */
typedef struct atari_ntsc_t
{
	ntsc_rgb_t table [atari_ntsc_color_count] [atari_ntsc_entry_size];
} atari_ntsc_t;

/* Initialize and adjust parameters. Can be called multiple times on the same
atari_ntsc_t object. */
void atari_ntsc_init( struct atari_ntsc_t*, atari_ntsc_setup_t const* setup );

/* Blit one or more scanlines of Atari 8-bit palette values to 16-bit 5-6-5 RGB output.
For every 7 output pixels, reads approximately 4 source pixels. Use constants below for
definite input and output pixel counts. */
void atari_ntsc_blit( struct atari_ntsc_t const*, unsigned char const* atari_in, long in_pitch,
		int out_width, int out_height, unsigned short* rgb_out, long out_pitch );

/* Useful values to use for output width and number of input pixels read */
enum {
	atari_ntsc_min_out_width  = 570, /* minimum width that doesn't cut off active area */
	atari_ntsc_min_in_width   = 320,
	
	atari_ntsc_full_out_width = 598, /* room for 8-pixel left & right overscan borders */
	atari_ntsc_full_in_width  = 336
};

/* supports 16-bit and 15-bit RGB output */
#ifndef ATARI_NTSC_RGB_BITS
	#define ATARI_NTSC_RGB_BITS 16
#endif


/* Atari800-specific: */

extern atari_ntsc_setup_t atari_ntsc_setup;

int atari_ntsc_Initialise(int *argc, char *argv[]);


#endif