First pass at snowflakes demo

software/apps/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_subdirectory(bad_apple)
 add_subdirectory(colour_terminal)
+add_subdirectory(christmas_snowflakes)
 add_subdirectory(dht_logging)
 add_subdirectory(dual_display)
 add_subdirectory(hello_dvi)

software/apps/christmas_snowflakes/CMakeLists.txt

@@ -0,0 +1,24 @@
+# Replace TMDS with 10 bit UART (same baud rate):
+# add_definitions(-DDVI_SERIAL_DEBUG=1)
+# add_definitions(-DRUN_FROM_CRYSTAL)
+
+add_executable(christmas_snowflakes
+	main.c
+)
+
+target_compile_options(christmas_snowflakes PRIVATE -Wall)
+
+target_compile_definitions(christmas_snowflakes PRIVATE
+	DVI_DEFAULT_SERIAL_CONFIG=${DVI_DEFAULT_SERIAL_CONFIG}
+	)
+
+target_link_libraries(christmas_snowflakes
+	pico_stdlib
+	pico_multicore
+	pico_util
+	libdvi
+	libsprite
+)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(christmas_snowflakes)

software/apps/christmas_snowflakes/main.c

@@ -0,0 +1,183 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#include "pico/stdlib.h"
+#include "pico/multicore.h"
+#include "hardware/clocks.h"
+#include "hardware/irq.h"
+#include "hardware/sync.h"
+#include "hardware/gpio.h"
+#include "hardware/vreg.h"
+
+#include "dvi.h"
+#include "dvi_serialiser.h"
+#include "common_dvi_pin_configs.h"
+
+#include "wikimedia_christmas_tree_in_field_320x240_rgb565.h"
+#include "snowflakes.h"
+
+#define SNOWFLAKE_SIZE 64
+#define N_SNOWFLAKE_IMAGES 8
+#define N_SPRITES 9
+
+#define RED_MASK 0xf800u
+#define GREEN_MASK 0x07e0u
+#define BLUE_MASK 0x001fu
+
+// DVDD 1.2V (1.1V seems ok too)
+#define FRAME_WIDTH 320
+#define FRAME_HEIGHT 240
+#define VREG_VSEL VREG_VOLTAGE_1_20
+#define DVI_TIMING dvi_timing_640x480p_60hz
+
+struct dvi_inst dvi0;
+
+void core1_main() {
+	dvi_register_irqs_this_core(&dvi0, DMA_IRQ_0);
+	while (queue_is_empty(&dvi0.q_colour_valid))
+		__wfe();
+	dvi_start(&dvi0);
+	dvi_scanbuf_main_16bpp(&dvi0);
+}
+
+// -----------------------------------------------------------------------------
+
+#define N_SCANLINE_BUFFERS 6
+uint16_t __attribute__((aligned(4))) static_scanbuf[N_SCANLINE_BUFFERS][FRAME_WIDTH];
+
+static inline uint16_t rgb565_lerp(uint32_t c0, uint32_t c1, uint alpha) {
+	return
+		(((c0 & RED_MASK  ) * (256 - alpha) + (c1 & RED_MASK  ) * alpha) >> 8 & RED_MASK   ) |
+		(((c0 & GREEN_MASK) * (256 - alpha) + (c1 & GREEN_MASK) * alpha) >> 8 & GREEN_MASK ) |
+		(((c0 & BLUE_MASK ) * (256 - alpha) + (c1 & BLUE_MASK ) * alpha) >> 8 & BLUE_MASK  );
+}
+
+static inline uint16_t rgb565_lerp_white(uint32_t c0, uint alpha) {
+	alpha = 256 - alpha;
+	c0 = ~c0;
+	c0 =
+		(((c0 & RED_MASK  ) * alpha >> 8) & RED_MASK  ) |
+		(((c0 & GREEN_MASK) * alpha >> 8) & GREEN_MASK) |
+		(((c0 & BLUE_MASK ) * alpha >> 8) & BLUE_MASK );
+	return ~c0;
+}
+
+static inline float uniform() {
+	return (float)rand() / RAND_MAX;
+}
+
+typedef struct {
+	float x, y;
+	float drift_x, drift_y;
+	float waft;
+	float waft_freq;
+	float waft_amplitude;
+	uint image_select;
+} snowflake_t;
+
+snowflake_t sprites[N_SPRITES];
+
+void update() {
+	for (int i = 0; i < N_SPRITES; ++i) {
+		snowflake_t *s = &sprites[i];
+		s->x += s->drift_x + sinf(s->waft) * s->waft_amplitude;
+		s->y += s->drift_y;
+		s->waft += s->waft_freq;
+		if (s->y >= FRAME_HEIGHT || s->x < -SNOWFLAKE_SIZE || s->x >= FRAME_WIDTH) {
+			s->y = -SNOWFLAKE_SIZE;
+			s->x = uniform() * (FRAME_HEIGHT - SNOWFLAKE_SIZE);
+			s->drift_x = uniform() * 2.f - 1.f;
+			s->drift_y = uniform() * 1.5f + 1.f;
+			s->waft = 0;
+			s->waft_freq = uniform() * 0.1f + 0.01f;
+			s->waft_amplitude = uniform() * 0.1f / s->waft_freq;
+			sprites[i].image_select = (rand() >> 8) % N_SNOWFLAKE_IMAGES;
+		}
+	}
+}
+
+void __scratch_x("render") render_scanline(uint16_t *scanbuf, uint raster_y) {
+	// Use DMA to copy in background line (for speed)
+	uint dma_chan = dma_claim_unused_channel(true);
+    dma_channel_config cfg = dma_channel_get_default_config(dma_chan);
+    channel_config_set_write_increment(&cfg, true);
+    dma_channel_configure(
+    	dma_chan,
+    	&cfg,
+    	scanbuf,
+    	&((const uint16_t*)wikimedia_christmas_tree_in_field_320x240)[raster_y * FRAME_WIDTH],
+    	FRAME_WIDTH / 2,
+    	true
+    );
+    dma_channel_wait_for_finish_blocking(dma_chan);
+    dma_channel_unclaim(dma_chan);
+
+	for (int s = 0; s < N_SPRITES; ++s) {
+		uint8_t *img = (uint8_t*)snowflakes + SNOWFLAKE_SIZE * SNOWFLAKE_SIZE * sprites[s].image_select;
+ 
+ 		// Check if sprite intersects scanline in y
+		uint i = raster_y - (uint)(int)sprites[s].y;
+		if (i >= SNOWFLAKE_SIZE)
+			continue;
+
+		for (int j = 0; j < SNOWFLAKE_SIZE; ++j) {
+			int x = (int)sprites[s].x + j;
+			if (x < 0)
+				continue;
+			if (x >= FRAME_WIDTH)
+				break;
+			scanbuf[x] = rgb565_lerp_white(
+				scanbuf[x],
+				img[j + SNOWFLAKE_SIZE * i]
+			);
+		}
+	}
+}
+
+// -----------------------------------------------------------------------------
+
+int main() {
+	vreg_set_voltage(VREG_VSEL);
+	sleep_ms(10);
+	set_sys_clock_khz(DVI_TIMING.bit_clk_khz, true);
+
+	setup_default_uart();
+
+	dvi0.timing = &DVI_TIMING;
+	dvi0.ser_cfg = DVI_DEFAULT_SERIAL_CONFIG;
+	dvi_init(&dvi0, next_striped_spin_lock_num(), next_striped_spin_lock_num());
+
+	for (int i = 0; i < N_SCANLINE_BUFFERS; ++i) {
+		void *bufptr = &static_scanbuf[i];
+		queue_add_blocking((void*)&dvi0.q_colour_free, &bufptr);
+	}
+
+	// DVI will start when first valid scanbuf is presented
+	multicore_launch_core1(core1_main);
+
+    for (int i = 0; i < N_SPRITES; ++i) {
+        // Initialise all sprites to out-of-bounds so update will sprinkle them from the top
+        sprites[i].x = 0;
+        sprites[i].y = 10 * FRAME_HEIGHT;
+        sprites[i].drift_x = 0;
+        sprites[i].drift_y = 0;
+        sprites[i].waft = 0;
+        sprites[i].waft_freq = 0;
+        sprites[i].waft_amplitude = 0;
+        sprites[i].image_select = 0;
+    }
+
+	uint frame_ctr = 0;
+	while (true) {
+		for (uint y = 0; y < FRAME_HEIGHT; ++y) {
+			uint16_t *scanbuf;
+			queue_remove_blocking_u32(&dvi0.q_colour_free, &scanbuf);
+			render_scanline(scanbuf, y);
+			queue_add_blocking_u32(&dvi0.q_colour_valid, &scanbuf);
+		}
+		update();
+		++frame_ctr;
+	}
+}

software/scripts/packtiles

@@ -6,7 +6,7 @@ import os
 import struct
 import sys
 
-FORMATS = ["argb1555", "rgab5515", "bgar5515", "rgb565", "argb1232", "ragb2132", "rgb332", "r2", "r1", "p8", "p4", "p2", "p1"]
+FORMATS = ["argb1555", "rgab5515", "bgar5515", "rgb565", "argb1232", "ragb2132", "rgb332", "r8", "r2", "r1", "p8", "p4", "p2", "p1"]
 
 def bytes_from_bitstream_le(bitstream):
 	accum = 0
@@ -85,6 +85,7 @@ rgb_formats = {
 	"argb1232": (8, ((6, 5), (4, 2), (1, 0), (7, 7))),
 	"ragb2132": (8, ((7, 6), (4, 2), (1, 0), (5, 5))),
 	"rgb332"  : (8, ((7, 5), (4, 2), (1, 0))),
+	"r8"      : (8, ((7, 0), (-1, 0), (-1, 0))),
 	"r2"      : (2, ((1, 0), (-1, 0), (-1, 0))),
 	"r1"      : (1, ((0, 0), (-1, 0), (-1, 0))),
 }