Add mdec/mdecimage example, psxpress fixes

1 files changed, 82 insertions, 0 deletions

diff --git a/examples/mdec/mdecimage/main.c b/examples/mdec/mdecimage/main.c
new file mode 100644
index 0000000..b59fdaf
--- /dev/null
+++ b/examples/mdec/mdecimage/main.c
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+/*
+ * PSn00bSDK MDEC static image example
+ * (C) 2022 spicyjpeg - MPL licensed
+ *
+ * This is a modified version of the graphics/rgb24 example showing how to feed
+ * run-length encoded data into the MDEC and retrieve a decoded 24bpp image. To
+ * keep the example simple no additional compression is applied (usually MDEC
+ * data would be Huffman encoded to save more space, with the initial
+ * decompression being done in software). A Python script is included to encode
+ * an image into the format expected by the MDEC; quality and file size can be
+ * tweaked by changing the quantization scales with the -y and -c arguments.
+ *
+ * Using the MDEC to decode static images can be useful for e.g. menu
+ * backgrounds or loading screens, where smaller file sizes are desirable even
+ * if quality is sacrificed.
+ */
+
+#include <stdint.h>
+#include <stddef.h>
+#include <psxgpu.h>
+#include <psxpress.h>
+#include <hwregs_c.h>
+
+extern const uint32_t	mdec_image[];
+extern const size_t		mdec_image_size;
+
+#define SCREEN_XRES 640
+#define SCREEN_YRES 480
+
+//#define BLOCK_SIZE 8	// Monochrome (8x8), 15bpp display
+//#define BLOCK_SIZE 12	// Monochrome (8x8), 24bpp display
+//#define BLOCK_SIZE 16	// Color (16x16), 15bpp display
+#define BLOCK_SIZE 24	// Color (16x16), 24bpp display
+
+int main(int argc, const char* argv[]) {
+	DISPENV disp;
+
+	ResetGraph(0);
+	DecDCTReset(0);
+
+	// Set up the GPU for 640x480 interlaced 24bpp output.
+	SetDefDispEnv(&disp, 0, 0, SCREEN_XRES, SCREEN_YRES);
+	disp.isrgb24 = 1;
+	disp.isinter = 1;
+
+	PutDispEnv(&disp);
+	SetDispMask(1);
+
+	// Start feeding image data to the MDEC. This doesn't immediately start the
+	// decoding, instead the MDEC will wait until a destination buffer is also
+	// set up.
+	MDEC0 = 0x30000000 | (mdec_image_size / 4); // 0x38000000 for 15bpp
+	DecDCTinRaw(mdec_image, mdec_image_size / 4);
+
+	// Fetch decoded data from the MDEC in vertical 8x480 or 16x480 "slices".
+	// This is necessary as the MDEC doesn't buffer an entire frame but only
+	// returns a series of square macroblocks, which can't be placed into VRAM
+	// with a single LoadImage() call.
+	//for (uint32_t x = 0; x < SCREEN_XRES; x += BLOCK_SIZE) {			// 15bpp
+	for (uint32_t x = 0; x < (SCREEN_XRES * 3 / 2); x += BLOCK_SIZE) {	// 24bpp
+		RECT     rect;
+		uint32_t slice[BLOCK_SIZE * SCREEN_YRES / 2];
+
+		rect.x = x;
+		rect.y = 0;
+		rect.w = BLOCK_SIZE;
+		rect.h = SCREEN_YRES;
+
+		// Configure the MDEC to output to the slice buffer and let it finish
+		// decoding a slice, then upload it to the framebuffer.
+		DecDCTout(slice, BLOCK_SIZE * SCREEN_YRES / 2);
+		DecDCToutSync(0);
+
+		LoadImage(&rect, (u_long *) slice);
+		DrawSync(0);
+	}
+
+	for (;;)
+		__asm__ volatile("");
+
+	return 0;
+}