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cvideo.c
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cvideo.c
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/*-----------------------------------------------
* Pico-Composite8 Composite Video, 8-bit output
*
* 2021-06-04 [email protected]
*-----------------------------------------------
*/
#include <stdlib.h>
//#include <stdio.h>
#include "memory.h"
#include "pico/stdlib.h"
#include "pico/multicore.h"
#include "hardware/pio.h"
#include "hardware/dma.h"
#include "hardware/irq.h"
void cvideo_configure_pio_dma(PIO pio, uint sm, uint dma_channel, size_t buffer_size_words);
void cvideo_dma_handler(void);
#include "cvideo.pio.h" // The assembled PIO code
#define width 512 // Bitmap width in pixels --- but there will be 2 pixels per byte
#define height 384 // Bitmap height in pixels
/*-------------------------------------------------------------------*/
/*------------------Video Standard-----------------------------------*/
/*-------------------------------------------------------------------*/
const int VIDEO_frame_lines = 525;
const int VIDEO_frame_lines_visible = 480;
const float VIDEO_aspect_ratio = 4.0/3.0;
//const float VIDEO_horizontal_freq = 15750.0;
const float VIDEO_horizontal_freq = 15734.0;
const float VIDEO_h_FP_usec = 1.5; // front porch
const float VIDEO_h_SYNC_usec = 4.7; // sync
const float VIDEO_h_BP_usec = 4.7; // back porch
const float VIDEO_h_EP_usec = 2.3; // equalizing pulse
/*-------------------------------------------------------------------*/
/*------------------Horizontal Derived-------------------------------*/
/*-------------------------------------------------------------------*/
const int HORIZ_visible_dots = VIDEO_frame_lines_visible * VIDEO_aspect_ratio; // full frame width
const float HORIZ_usec = 1000000.0 / VIDEO_horizontal_freq;
const float HORIZ_usec_dot = (HORIZ_usec - VIDEO_h_FP_usec - VIDEO_h_SYNC_usec - VIDEO_h_BP_usec) / HORIZ_visible_dots;
const int HORIZ_dots = HORIZ_usec / HORIZ_usec_dot;
const int HORIZ_bytes = HORIZ_dots / 2; // two dots per byte
const int HORIZ_FP_bytes = VIDEO_h_FP_usec / HORIZ_usec_dot / 2;
const int HORIZ_SYNC_bytes = VIDEO_h_SYNC_usec / HORIZ_usec_dot / 2;
const int HORIZ_BP_bytes = VIDEO_h_BP_usec / HORIZ_usec_dot / 2;
const int HORIZ_EP_bytes = VIDEO_h_EP_usec / HORIZ_usec_dot / 2; // equalizing pulse during vertical sync
const int HORIZ_pixel_start = ((HORIZ_visible_dots - width) / 2) / 2 + HORIZ_SYNC_bytes + HORIZ_BP_bytes;
/*-------------------------------------------------------------------*/
/*------------------Vertical Derived---------------------------------*/
/*-------------------------------------------------------------------*/
const int VERT_scanlines = VIDEO_frame_lines / 2; // one field
const int VERT_vblank = (VIDEO_frame_lines - VIDEO_frame_lines_visible) / 2; // vertical blanking, one field
const int VERT_border = (VERT_scanlines - VERT_vblank - height/2) / 2;
const int VERT_bitmap = height/2;
/*-------------------------------------------------------------------*/
/*------------------PIO----------------------------------------------*/
/*-------------------------------------------------------------------*/
const float PIO_clkdot = 1.0; // PIO instructions per dot
const float PIO_sysclk = 125000000.0; // default Pico system clock
const float PIO_clkdiv = PIO_sysclk / VIDEO_horizontal_freq / PIO_clkdot / HORIZ_dots;
/*-------------------------------------------------------------------*/
/*------------------Gray Scale---------------------------------------*/
/*-------------------------------------------------------------------*/
// NTSC in IRE units+40: SYNC = 0; BLANK = 40; BLACK = 47.5; WHITE = 140
const int WHITE = 15;
const int BLACK = 15.0 / 140.0 * 47.5;
const int BLANK = 15.0 / 140.0 * 40.0;
const int GRAY = (WHITE + BLACK)/ 3;
const int SYNC = 0;
#define border_colour BLACK
#define state_machine 0 // The PIO state machine to use
uint dma_channel; // DMA channel for transferring hsync data to PIO
uint vline = 9999; // Current video line being processed
uint bline = 0; // Line in the bitmap to fetch
uint field = 1; // field, even/odd
uint lifeGen = 0; // alternating life generations
int bmIndex = 0;
int bmCount = 0;
// bitmap buffer
unsigned char * life[2];
unsigned char * vsync_ll; // buffer for a vsync line with a long/long pulse
unsigned char * vsync_ss; // Buffer for an equalizing line with a short/short pulse
unsigned char * vsync_bb; // Buffer for a vsync blanking
unsigned char * vsync_ssb; // Buffer and a half for equalizing/blank line
unsigned char * border; // Buffer for a vsync line for the top and bottom borders
unsigned char * pixel_buffer[2]; // Double-buffer for the pixel data scanlines
volatile bool changeBitmap = false;
/*-------------------------------------------------------------------*/
void setLifeCell(uint g, uint x, uint y, uint v) {
uint LorR = x & 0x01;
uint Lx = x/2;
uint i = y*width/2 + Lx;
uint Lv = v > 0 ? WHITE : BLACK;
if ( LorR ) {
*(life[g]+i) = (*(life[g]+i) & 0xf0) | Lv;
} else {
*(life[g]+i) = (*(life[g]+i) & 0x0f) | Lv<<4;
}
}
/*-------------------------------------------------------------------*/
int getLifeCell(uint g, int x, int y) {
// handle wrap-around
//if ( y >= height ) y -= height;
//if ( y < 0 ) y += height;
//if ( x >= width ) x -= width;
//if ( x < 0 ) x += width;
// don't handle wrap-around
if ( y >= height || y < 0 ) return 0;
if ( x >= width || x < 0 ) return 0;
uint LorR = x & 0x01;
uint Lx = x/2;
uint i = y*width/2 + Lx;
uint Lv;
if ( LorR ) {
Lv = (*(life[g]+i) & 0x0f);
} else {
Lv = (*(life[g]+i) & 0xf0) >>4;
}
return( Lv == WHITE );
}
/*-------------------------------------------------------------------*/
void second_core() {
uint lifeNext = 1;
uint lifeCounter = 0;
uint lifeBit = 0;
uint lifeByte = 0;
uint64_t emptyGlob;
for ( int i=0; i<sizeof(emptyGlob); i++ ) {
emptyGlob = (emptyGlob<<4)|BLACK;
emptyGlob = (emptyGlob<<4)|BLACK;
}
// seed
//#include "gosperglidergun.h"
//#include "bunnies.h"
//#include "blom.h"
//#include "homer.h"
#include "multuminparvo.h"
int lastCol = 0;
int thisCol = 0;
int nextCol = 0;
while (true) {
// work on the next generation
lifeNext = (lifeGen + 1) & 0x01;
// for every cell, count neighbors in current generation
// ...for each row
for ( int row = 1; row < height-1; row++ ) {
// get the globs ready
uint64_t * glob1 = (uint64_t *)(life[lifeGen]+((row-1)*width/2));
uint64_t * glob2 = (uint64_t *)(life[lifeGen]+((row)*width/2));
uint64_t * glob3 = (uint64_t *)(life[lifeGen]+((row+1)*width/2));
uint64_t * glob4 = (uint64_t *)(life[lifeNext]+((row)*width/2));
// sum the cols...
lastCol = getLifeCell(lifeGen,-1,row-1) + getLifeCell(lifeGen,-1,row) + getLifeCell(lifeGen,-1,row+1);
// do each glob on row
int col = 0;
for ( int g = 0; g < width/16; g++ ) {
int c = 0;
if ( lastCol == 0 && *(glob1+g) == emptyGlob && *(glob2+g) == emptyGlob && *(glob3+g) == emptyGlob ) {
// there's nothing to process, skip to end of glob
*(glob4+g) = emptyGlob;
c = 15;
col += c;
}
thisCol = getLifeCell(lifeGen,col,row-1) + getLifeCell(lifeGen,col,row) + getLifeCell(lifeGen,col,row+1);
for ( ; c < 16; c++ ) {
nextCol = getLifeCell(lifeGen,col+1,row-1) + getLifeCell(lifeGen,col+1,row) + getLifeCell(lifeGen,col+1,row+1);
int currentCell = getLifeCell(lifeGen, col, row);
int liveNeighbors = lastCol + thisCol + nextCol - currentCell;
setLifeCell(lifeNext, col, row, currentCell);
if ( liveNeighbors < 2 ) setLifeCell(lifeNext, col, row, 0);
if ( liveNeighbors > 3 ) setLifeCell(lifeNext, col, row, 0);
if ( liveNeighbors == 3 ) setLifeCell(lifeNext, col, row, 1);
lastCol = thisCol;
thisCol = nextCol;
col++;
}
}
}
lifeGen = lifeNext;
//sleep_ms(1000); // sleep_ms() causes a visible glitch
//busy_wait_us(1000000);
}
}
/*-------------------------------------------------------------------*/
int main() {
// stdio_init_all();
// sleep_ms(2000);
// printf("Start of program\n");
// for debug
gpio_init(8);
gpio_set_dir(8,GPIO_OUT);
gpio_init(9);
gpio_set_dir(9,GPIO_OUT);
gpio_init(10);
gpio_set_dir(10,GPIO_OUT);
// two pixels(dots) per byte
uint BLANK2 = BLANK | BLANK << 4;
uint BLACK2 = BLACK | BLACK << 4;
uint GRAY2 = GRAY | GRAY << 4;
uint WHITE2 = WHITE | WHITE << 4;
life[0] = (unsigned char *)malloc(width*height/2);
memset(life[0], BLACK2, height*width/2);
life[1] = (unsigned char *)malloc(width*height/2);
memset(life[1], BLACK2, height*width/2);
multicore_launch_core1(second_core);
// two pixels(dots) per byte
vsync_ll = (unsigned char *)malloc(HORIZ_bytes);
memset(vsync_ll, SYNC, HORIZ_bytes); // vertical sync/serrations
memset(vsync_ll + (HORIZ_bytes>>1) - HORIZ_EP_bytes, BLANK2, HORIZ_EP_bytes);
memset(vsync_ll + HORIZ_bytes - HORIZ_EP_bytes, BLANK2, HORIZ_EP_bytes);
vsync_ss = (unsigned char *)malloc(HORIZ_bytes);
memset(vsync_ss, BLANK2, HORIZ_bytes); // vertical equalizing
memset(vsync_ss, SYNC, HORIZ_EP_bytes);
memset(vsync_ss + (HORIZ_bytes>>1), SYNC, HORIZ_EP_bytes);
vsync_bb = (unsigned char *)malloc(HORIZ_bytes);
memset(vsync_bb, BLANK2, HORIZ_bytes); // vertical blanking
memset(vsync_bb, SYNC, HORIZ_SYNC_bytes);
vsync_ssb = (unsigned char *)malloc(HORIZ_bytes+(HORIZ_bytes>>1));
memset(vsync_ssb, BLANK2, HORIZ_bytes + (HORIZ_bytes>>1)); // vertical equalizing/blanking
memset(vsync_ssb, SYNC, HORIZ_EP_bytes);
memset(vsync_ssb + (HORIZ_bytes>>1), SYNC, HORIZ_EP_bytes);
// This bit pre-builds the border scanline and pixel buffers
border = (unsigned char *)malloc(HORIZ_bytes);
memset(border, GRAY2, HORIZ_bytes); // Fill the border with the border colour
memset(border, SYNC, HORIZ_SYNC_bytes); // Add the hsync pulse
memset(border + HORIZ_SYNC_bytes, BLANK2, HORIZ_BP_bytes);
memset(border + HORIZ_bytes - HORIZ_FP_bytes, BLANK2, HORIZ_FP_bytes); // front porch
pixel_buffer[0] = (unsigned char *)malloc(HORIZ_bytes);
memcpy(pixel_buffer[0], border, HORIZ_bytes); // pixel buffer
pixel_buffer[1] = (unsigned char *)malloc(HORIZ_bytes);
memcpy(pixel_buffer[1], border, HORIZ_bytes); // pixel buffer
// Initialise the PIO
PIO pio = pio0;
uint offset = pio_add_program(pio, &cvideo_program); // Load up the PIO program
pio_sm_set_enabled(pio, state_machine, false); // Disable the PIO state machine
pio_sm_clear_fifos(pio, state_machine); // Clear the PIO FIFO buffers
cvideo_initialise_pio(pio, state_machine, offset, 4, 4, PIO_clkdiv); // Initialise the PIO (function in cvideo.pio)
dma_channel = dma_claim_unused_channel(true); // Claim a DMA channel for the hsync transfer
cvideo_configure_pio_dma(pio, state_machine, dma_channel, HORIZ_bytes); // Hook up the DMA channel to the state machine
// And kick everything off
cvideo_dma_handler(); // Call the DMA handler as a one-off to initialise it
pio_sm_set_enabled(pio, state_machine, true); // Enable the PIO state machine
while (true) { // And then just loop doing nothing
tight_loop_contents();
}
}
/*-------------------------------------------------------------------*/
// The DMA interrupt handler
// This is triggered by DMA_IRQ_0
void cvideo_dma_handler(void) {
if ( ++vline <= VERT_scanlines ) {
} else {
vline = 0;
bline = 0;
field = ++field & 0x01;
}
while (true) {
if ( vline <= VERT_vblank ) {
switch(vline) {
case 0:
if ( field ) {
// odd field - blank, full line
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
} else {
// even field - blank, half line
dma_channel_set_trans_count(dma_channel, HORIZ_bytes/2, false);
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
}
break;
case 1:
dma_channel_set_trans_count(dma_channel, HORIZ_bytes, false); // reset transfer size
case 2 ... 3:
// send 3 vsync_ss - 'equalizing pulses'
dma_channel_set_read_addr(dma_channel, vsync_ss, true);
break;
case 4 ... 6:
// send 3 vsync_ll - 'vertical sync/serrations'
dma_channel_set_read_addr(dma_channel, vsync_ll, true);
break;
case 7 ... 8:
// send 3 vsync_ss - 'equalizing pulses'
dma_channel_set_read_addr(dma_channel, vsync_ss, true);
break;
case 9:
if ( field ) {
// odd field - equalizing pulse, full line
dma_channel_set_read_addr(dma_channel, vsync_ss, true);
} else {
//even field - equalizing pulse, line and a half
dma_channel_set_trans_count(dma_channel, HORIZ_bytes + HORIZ_bytes/2, false);
dma_channel_set_read_addr(dma_channel, vsync_ssb, true);
}
break;
case 10:
// everything back to normal
dma_channel_set_trans_count(dma_channel, HORIZ_bytes, false); // reset transfer size
default:
// send BLANK till end of vertical blanking
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
break;
}
break;
}
if ( vline <= VERT_vblank + VERT_border ) {
if (changeBitmap) {
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
} else {
dma_channel_set_read_addr(dma_channel, border, true);
if ( vline == VERT_vblank + VERT_border ) {
memcpy(pixel_buffer[bline & 1] + HORIZ_pixel_start, life[lifeGen]+(bline*2+field)*width/2, width/2);
}
}
break;
}
if ( vline <= VERT_vblank + VERT_border + VERT_bitmap ) {
if (changeBitmap) {
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
} else {
dma_channel_set_read_addr(dma_channel, pixel_buffer[bline++ & 1], true); // Set the DMA to read from one of the pixel_buffers
memcpy(pixel_buffer[bline & 1] + HORIZ_pixel_start, life[lifeGen]+(bline*2+field)*width/2, width/2); // And memcpy the next scanline
}
break;
}
// otherwise, just output border until end of scanlines
if (changeBitmap) {
dma_channel_set_read_addr(dma_channel, vsync_bb, true);
} else {
dma_channel_set_read_addr(dma_channel, border, true);
}
break;
}
// Finally, clear the interrupt request ready for the next horizontal sync interrupt
dma_hw->ints0 = 1u << dma_channel;
}
/*-------------------------------------------------------------------*/
// Configure the PIO DMA
// Parameters:
// - pio: The PIO to attach this to
// - sm: The state machine number
// - dma_channel: The DMA channel
// - buffer_size_words: Number of bytes to transfer
//
void cvideo_configure_pio_dma(PIO pio, uint sm, uint dma_channel, size_t buffer_size_words) {
pio_sm_clear_fifos(pio, sm);
dma_channel_config c = dma_channel_get_default_config(dma_channel);
channel_config_set_transfer_data_size(&c, DMA_SIZE_8);
channel_config_set_read_increment(&c, true);
channel_config_set_dreq(&c, pio_get_dreq(pio, sm, true));
dma_channel_configure(dma_channel, &c,
&pio->txf[sm], // Destination pointer
NULL, // Source pointer
buffer_size_words, // Number of transfers
false // Start flag (true = start immediately)
);
dma_channel_set_irq0_enabled(dma_channel, true);
irq_set_exclusive_handler(DMA_IRQ_0, cvideo_dma_handler);
irq_set_enabled(DMA_IRQ_0, true);
}