ben-blinkenlights/ubb-la/gui.c

/*
 * gui.c - Graphical output for ubb-la
 *
 * Written 2013 by Werner Almesberger
 * Copyright 2013 Werner Almesberger
 *
 * 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.
 */

#include <stdint.h>
#include <stdlib.h>

#include "SDL.h"
#include "SDL_gfxPrimitives.h"

#include "gui.h"


#if 0
#define	DEBUG(fmt, ...)	fprintf(stderr, fmt, __VA_ARGS__)
#else
#define	DEBUG(fmt, ...)
#endif


#define XRES	320	/* canvas width */
#define YRES	240	/* canvas height */

#define	LEVEL_RGBA	0xffff00ff
#define	BOUNCE_RGBA	0xff8080ff

#define	CH_XOFF		30
#define	CH_YOFF		30
#define	CH_SKIP		16
#define	CH_HEIGHT	8

#define	MAX_ZOOM	3

#define	REPEAT_DELAY_MS		300
#define	REPEAT_INTERVAL_MS	30

static SDL_Surface *surf;


/* ----- SDL initialization and screen-wide functions ---------------------- */


void gui_init(void)
{
	if (SDL_Init(SDL_INIT_VIDEO) < 0) {
		fprintf(stderr, "SDL_init: %s\n", SDL_GetError());
		exit(1);
	}
	atexit(SDL_Quit);

	surf = SDL_SetVideoMode(XRES, YRES, 0, SDL_SWSURFACE);
	if (!surf) {
		fprintf(stderr, "SDL_SetVideoMode: %s\n", SDL_GetError());
		exit(1);
	}

	SDL_EnableKeyRepeat(REPEAT_DELAY_MS, REPEAT_INTERVAL_MS);
}


static void clear(void)
{
	SDL_LockSurface(surf);
	SDL_FillRect(surf, NULL, SDL_MapRGB(surf->format, 0, 0, 0));
}


static void update(void)
{
	SDL_UnlockSurface(surf);
	SDL_UpdateRect(surf, 0, 0, 0, 0);
}


/* ----- Waveform elements ------------------------------------------------- */


static inline int ch_y(int ch, int v)
{
	return CH_YOFF+CH_SKIP*ch+(v ? 0 : CH_HEIGHT);
}


static void bounce(int x, int ch)
{
	vlineColor(surf, x, ch_y(ch, 0), ch_y(ch, 1), BOUNCE_RGBA);
}


static void change(int x, int ch)
{
	vlineColor(surf, x, ch_y(ch, 0), ch_y(ch, 1), LEVEL_RGBA);
}


static void level(int x0, int x1, int ch, int v)
{
	if (x0 == x1)
		pixelColor(surf, x0, ch_y(ch, v), LEVEL_RGBA);
	else
		hlineColor(surf, x0, x1, ch_y(ch, v), LEVEL_RGBA);
}


/* ----- Show (part of) a buffer ------------------------------------------- */


static void show_buffer_zoom_in(const uint8_t *buf, int skip, int nibbles,
    int x0, int x1)
{
	int f = (x1-x0)/(nibbles-skip);
	int x, i, j;
	int last[4] = { -1, -1, -1, -1};
	uint8_t v, bit;

	DEBUG("in: %d-%d (%d) Sa %d-%d (%d) pix %d f (%d)\n",
	    skip, nibbles, nibbles-skip, x0, x1, x1-x0, f, f*(nibbles-skip));
	x = x0;
	for (i = skip; i != nibbles; i++) {
		v = (buf[i >> 1] >> 4*(~i & 1)) & 0xf;
		for (j = 0; j != 4; j++) {
			bit = (v >> j) & 1;
			if (bit == last[j] || last[j] == -1) {
				level(x, x+f-1, j, bit);
			} else {
				change(x, j);
				level(x+1, x+f-1, j, bit);
			}
			last[j] = bit;
		}
		x += f;
	}
}


static void show_buffer_zoom_out(const uint8_t *buf, int skip, int nibbles,
    int x0, int x1)
{
	int f = (nibbles-skip)/(x1-x0);
	int x;
	int i = skip, n, j;
	int changes[4], last[4] = { -1, -1, -1, -1}, next[4];
	uint8_t v, bit;

	DEBUG("out: %d-%d (%d) Sa %d-%d (%d) pix %d f (%d)\n",
	    skip, nibbles, nibbles-skip, x0, x1, x1-x0, f, f*(x1-x0));
	for (x = x0; x != x1; x++) {
		n = i+f;
		for (j = 0; j != 4; j++) {
			next[j] = last[j];
			changes[j] = 0;
		}
		while (i != n) {
			v = (buf[i >> 1] >> 4*(~i & 1)) & 0xf;
			for (j = 0; j != 4; j++) {
				bit = (v >> j) & 1;
				if (bit != next[j]) {
					changes[j]++;
					next[j] = bit;
				}
			}
			i++;
		}
		for (j = 0; j != 4; j++) {
			if (changes[j] > 1)
				bounce(x, j);
			else if (!changes[j] || last[j] == -1)
				level(x, x, j, next[j]);
			else
				change(x, j);
			last[j] = next[j];
		}
	}
}


static void show_buffer(const uint8_t *buf, int skip, int nibbles,
    int x0, int x1, int zoom, int pos)
{
	int xm, w, p0, p1;
	int d, dp;

	xm = (x0+x1) >> 1;
	dp = pos-((nibbles+skip) >> 1);
	if (zoom < 0) {
		w = (nibbles-skip) >> -zoom;
		p0 = xm-(w >> 1)-(dp >> -zoom);
		p1 = xm+((w+1) >> 1)-(dp >> -zoom);
		if (p0 < x0) {
			skip += (x0-p0) << -zoom;
			p0 = x0;
		}
		if (p1 > x1) {
			nibbles -= (p1-x1) << -zoom;
			p1 = x1;
		}
		show_buffer_zoom_out(buf, skip, nibbles, p0, p1);
	} else {
		w = (nibbles-skip) << zoom;
		p0 = xm-(w >> 1)-(dp << zoom);
		p1 = xm+((w+1) >> 1)-(dp << zoom);
		if (p0 < x0) {
			d = ((x0-p0)+(1 << zoom)-1) >> zoom;
			skip += d;
			p0 += d << zoom;
		}
		if (p1 > x1) {
			d = ((p1-x1)+(1 << zoom)-1) >> zoom;
			nibbles -= d;
			p1 -= d << zoom;
		}
		show_buffer_zoom_in(buf, skip, nibbles, p0, p1);
	}
}


/* ----- Main event loop --------------------------------------------------- */


static int pos_step(int zoom)
{
	return 1 << (MAX_ZOOM-zoom+1);
}


void gui(const uint8_t *buf, int skip, int nibbles)
{
	SDL_Event event;
	int pos = (skip+nibbles) >> 1;
	int zoom;	/* < 0: zoom out; 0: 1 pixel = 1 sample; > 1: zoom in */
	int min_zoom = 0;

	while (XRES-CH_XOFF < (nibbles-skip) >> -min_zoom)
		min_zoom--;
	zoom = min_zoom;
	while (1) {
		clear();
		show_buffer(buf, skip, nibbles, CH_XOFF, XRES, zoom, pos);
		update();

		while (1) {
			SDL_WaitEvent(&event);
			switch (event.type) {
			case SDL_KEYDOWN:
				switch (event.key.keysym.sym) {
				case SDLK_UP:
					if (zoom < MAX_ZOOM)
						zoom++;
					break;
				case SDLK_DOWN:
					if (zoom > min_zoom)
						zoom--;
					break;
				case SDLK_LEFT:
					pos -= pos_step(zoom);
					if (pos < 0)
						pos = 0;
					break;
				case SDLK_RIGHT:
					pos += pos_step(zoom);
					if (pos > nibbles-1)
						pos = nibbles-1;
					break;
				case SDLK_RETURN:
				case SDLK_q:
					return;
				default:
					printf("%x\n", event.key.keysym.sym);
					continue;
				}
				break;
			case SDL_QUIT:
				return;
			default:
				continue;
			}	
			break;
		}
	}
}