Update to rev5, implement decompression.

src/fill.s

@@ -6,22 +6,21 @@ vera_data0 := $9f23
 .import popa
 .segment "CODE"
 _fill_vera:
-	sta vera_fill_data
-	jsr popa
-	sta max
-	lda max
-	cmp #0
-	beq @end
+	sta vera_fill_data ; Save the value to fill the vera with
+	jsr popa ; Get the length parameter
+	sta max ; Store the max value
+	cmp #0  ; Make sure it's not 0
+	beq @end ; If it is, we're already done
 @fill:
-	ldx #0
-	lda vera_fill_data
+	ldx #0 ; Initialize X
+	lda vera_fill_data ; Load the fill value
 @loop:
-	sta vera_data0
-	inx
-	cpx max
-	bne @loop
+	sta vera_data0 ; Store the fill value
+	inx ; Increment X
+	cpx max ; Compare it against the maximum value
+	bne @loop ; If it's not the max yet, do it again
 @end:
-	rts
+	rts ; We're done!
 .segment "BSS"
 max:
 	.res 1

src/macptr.s

@@ -7,30 +7,31 @@ r1 := $04
 r1l:= $04
 r1h:= $05
 .segment "CODE"
+; ASM wrapper for MACPTR
 _cx16_k_macptr:
-	sta r0l
+	sta r0l ; Store pointer in ZP
 	stx r0h
-	jsr popa
+	jsr popa ; Store increment boolean
 	sta r1l
-	jsr popa
+	jsr popa ; Store size byte
 	sta r1h
-	ldx r0l
+	ldx r0l ; Load parameters
 	ldy r0h 
 	lda r1l
-	beq @increment
-	clc
-	jmp @loadregs
+	beq @increment ; If A is 0, set the carry flag
+	clc ; Otherwise clear it
+	jmp @loadregs ; And don't set it again
 @increment:
-	sec
+	sec ; Set the carry flag
 @loadregs:
-	lda r1h
-	jsr $FF44
-	bcs @error
-	txa
+	lda r1h ; Load the size parameter
+	jsr $FF44 ; Call MACPTR
+	bcs @error ; If there was an error, return 0
+	txa ; Otherwise, set up registers to hold the return value
 	sty r0
 	ldx r0
 	rts
 @error:
-	lda #0
+	lda #0 ; Return 0 in case of error
 	ldx #0
 	rts

src/main.c

@@ -5,98 +5,138 @@
 #include <cbm.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <string.h>
 #include "vera.h"
 #include "macptr.h"
 #include "debug.h"
+#include "memory_decompress.h"
 #include "fill.h"
 uint8_t palette[512];
 uint8_t vera_bit_depth;
 uint8_t bitdepth;
 uint16_t width, height;
+bool compress;
+bool direct_to_vera;
+uint16_t imgdatastart;
 uint32_t imgdatabytes;
 uint8_t pixels_per_byte;
-uint8_t filleridx = 255;
+uint8_t borderidx = 255;
 bool over320;
 uint8_t oldhscale, oldvscale;
 uint8_t significant_palette_entries;
 uint8_t significant_palette_start;
+uint8_t *image_start = BANK_RAM;
+/// @brief Reads a 16 bit little endian value from LFN 2
+/// @return The 16 bit value
 uint16_t read16() {
 	cbm_k_chkin(2);
 	return ((cbm_k_chrin())) | ((uint16_t)cbm_k_chrin() << 8);
 }
+/// @brief Reads an 8 bit value and returns it as a character
+/// @return The character
 char readchar() {
 	cbm_k_chkin(2);
 	return cbm_k_chrin();
 }
+/// @brief Reads an unsigned 8 bit value and returns it as is
+/// @return The unsigned 8 bit value
 uint8_t read8() {
 	cbm_k_chkin(2);
 	return cbm_k_getin();
 }
+/// @brief Checks if the header in LFN 2 is correct
+/// @return True if it is, false otherwise
 bool checkheader() {
-	char header[4] = {0x42, 0x4D, 0x58, 0}; // X16BM
-	char tested[4] = {0, 0, 0, 0};
+	char header[4] = {0x42, 0x4D, 0x58, 0}; // BMX
+	char tested[4] = {0, 0, 0, 0}; // The tested values, for debugging
 	uint8_t i = 0;
-	bool valid = true;
+	bool valid = true; // Set to true so that if it's wrong, the loop can set it to false, but if it's correct, the loop doesn't have to set it
 	char chr = 0;
 	printf("Reading magic bytes...\n");
+	// Check the magic bytes one-by-one
 	for (; i < 3; i++) {
-		chr = readchar();
-		tested[i] = chr;
+		chr = readchar(); // Get a character
+		tested[i] = chr; // Put it in the tested value list
 		printf("%2x%s", chr, i >= 4 ? "\n" : ", ");
-		if (chr != header[i]) {
+		if (chr != header[i]) { // Check the value
 			valid = false;
 		}
 	}
+	// Make sure the tested values don't contain any unprintable characters
 	for (i = 0; i < 3; i++) {
 		if (tested[i] < 0x20 || tested[i] >= 0x7F) {
 			tested[i] = '.';
 		}
 	}
-	printf("%s%c=%s\n", tested, valid ? '=' : '!', header);
+	printf("%s%c=%s\n", tested, valid ? '=' : '!', header); // Display the comparison
 	return valid;
 }
+/// @brief Updates the scale of the VERA based on the minimum required width/height to display the image
 void updatescale() {
 	uint8_t hscale;
 	uint8_t vscale;
+	// Set DCSEL to 0
 	VERA.control &= 0b10000001;
+	// Get the scale to check against and later set back to
 	hscale = VERA.display.hscale;
 	vscale = VERA.display.vscale;
+	// Back up the current scale
 	oldhscale = hscale;
 	oldvscale = vscale;
+	// If it's over 320, the scale's probably correct.
 	if (over320) return;
+	// Make sure the scale doesn't end up showing garbage data.
 	if (hscale > 64) VERA.display.hscale = 64;
 	if (vscale > 64) VERA.display.vscale = 64;
 }
+/// @brief Restores the scale to what it was before updating it to fit the image
 void restorescale() {
 	VERA.control &= 0b10000001;
 	VERA.display.hscale = oldhscale;
 	VERA.display.vscale = oldvscale;
 }
+/// @brief Loads and uploads an image to the VERA
+/// @param filename The file to load
+/// @return 0 on success, exit code on failure
 int uploadimage(const char *filename) {
+	// Used for decompression.
+	uint8_t *image_end = BANK_RAM;
+	// 16 bit variables
 	size_t i = 0, j = 0, x = 0, y = 0, value = 0, bitmask = 0;
+	// Variables for the VERA width and height values
 	size_t vera_w = 320, vera_h = 240;
+	// The max address of the VERA
 	uint16_t vera_max = 0;
+	// 32 bit variables, used sparingly
 	uint32_t tmp = 0, vera_max_32 = 0;
-	uint16_t vera_adr_bak;
-	uint8_t vera_adr_h_bak;
+	// The bank the VERA will be at when the operation finishes
 	bool vera_max_bank = 1;
+	// Base layer config
 	uint8_t config = 0b00000100;
+	// The counter for the amount of bytes read
 	uint16_t bytes_read;
+	// The version of the BMX format
 	uint8_t version;
+	// True if all palette entries are significant
 	bool all_significant;
+	// Open the file
 	cbm_k_setnam(filename);
 	cbm_k_setlfs(2, 8, 2);
 	cbm_k_open();
+	// Check if the open was successful
 	if (cbm_k_readst()) {
 		printf("Error opening file.\n");
 		return 1;
 	}
+	// Make sure it's a BMX file
 	if (!checkheader()) {
 		printf("Invalid file!\n");
 		return 1;
 	}
+	// Read the header
 	version = read8();
 	bitdepth = read8();
+	// Verify the bitdepth
 	if (bitdepth == 0) {
 		printf("Error: bitdepth was 0.\n");
 		return 1;
@@ -104,19 +144,18 @@ int uploadimage(const char *filename) {
 	vera_bit_depth = read8();
 	vera_bit_depth &= 0b11;
 	config |= vera_bit_depth;
-	if (vera_bit_depth > 3) {
-		printf("Error: VERA bit depth was invalid!\n");
-	}
+	// Calculate the amount of pixels that can fit in a byte, used later
 	pixels_per_byte = 8 / bitdepth;
-	printf("Bit depth: %u => %u pixels per byte\n", bitdepth, pixels_per_byte);
-	width = read16();
+	printf("Bit depth: %u => %u pixels per byte\n", bitdepth, pixels_per_byte); // Debugging
+	width = read16(); // Get the image dimensions
 	height = read16();
 	printf("Width: %u, height: %u\n", width, height);
+	// Make sure the later update_scale call sets the correct scale
 	over320 = width > 320 || height > 240;
-	filleridx = read8();
-	printf("Border color: %02x\n", filleridx);
+	// Calculate the amount of bytes used within the image
 	imgdatabytes = ((uint32_t)width * (uint32_t)height) / (uint32_t)pixels_per_byte;
 	printf("Bytes: %lu\n", imgdatabytes);
+	// Get the list of significant palette entires
 	significant_palette_entries = read8();
 	significant_palette_start = read8();
 	if (significant_palette_entries == 0) {
@@ -126,60 +165,104 @@ int uploadimage(const char *filename) {
 	} else {
 		printf("%u palette entries significant\nstarting at %u.\n", significant_palette_entries, significant_palette_start);
 	}
+	imgdatastart = read16();
+	--imgdatastart;
+	printf("Image starts at 0-indexed offset %4x\n", imgdatastart);
+	direct_to_vera = width == vera_w && height == vera_h;
+	if ((int8_t)read8() == -1) {
+		compress = true;
+	};
 	printf("Skipping reserved bytes...\n");
-	for (i = 0; i < 19; i++) {
+	for (i = 0; i < 16; i++) {
 		read8();
 	}
+	// Load the border color
+	borderidx = read8();
+	printf("Border color: %02x\n", borderidx);
 	printf("Reading palette entries...\n");
-	for (i = 0; i < 512; i++) {
+	for (i = 0; i < (uint16_t)significant_palette_entries*2; i++) {
 		j = i >> 1;
-		if (all_significant || j >= significant_palette_start && j <= significant_palette_entries) {
+		// Only load the required palette entries
+		if (all_significant || j >= significant_palette_start && j < significant_palette_start+significant_palette_entries || j == borderidx) {
 			palette[i] = read8();
 		} else {
 			read8();
 			palette[i] = get_from_backed_up_palette(i);
 		}
 	}
+	// If the VERA was set up for a 640p image, make sure to keep track of that
 	if (over320) {
 		vera_w *= 2;
 		vera_h *= 2;
 	}
+	// Calculate the maximum address and bank
 	vera_max_32 = ((uint32_t)vera_w * (uint32_t)vera_h)/(uint32_t)pixels_per_byte;
+	// Get just the max address
 	vera_max = vera_max_32;
+	// ... and the max bank all by itself
 	vera_max_bank = vera_max_32 >> 16;
+	// Update the VERA layer config
 	VERA.layer0.config = config;
+	// Make sure the TILEW value is set up correctly
 	VERA.layer0.tilebase = over320 ? 1 : 0;
-	printf("Loading image bytes: $%lx\n", imgdatabytes);
+	// Debugging
+	printf("Loading %simage bytes: $%lx\n", compress ? "compressed " : "", imgdatabytes);
 	printf("Image width: %u, image height: %u\npixels per byte: %u\n", width, height, pixels_per_byte);
+	i = 0;
+	// Calculate the border value.
+	value = 0;
+	bitmask = (1 << bitdepth) - 1;
+	
+	if (compress && !direct_to_vera) {
+		printf("Error: The image cannot be loaded due to limitations in memory_decompress.");
+		return 1;
+	}
+	for (i = 0; i < pixels_per_byte; i++) {
+		value |= (borderidx & bitmask) << (i * bitdepth);
+	}
+	if (compress) {
+		RAM_BANK = 1;
+		do {
+			i = cx16_k_macptr(0, true, image_end);
+			image_end += i;
+			if (RAM_BANK > 1) {
+				printf("Error: Cannot decompress memory because compressed data is too large.\n");
+				return 1;
+			}
+			if (i == 0) {
+				break;
+			}
+		} while (i != 0);
+	}
+	// Set up the VERA's data0 address
 	VERA.control &= ~0b1;
 	VERA.address = 0;
 	VERA.address_hi = 0b00010000;
-	i = 0;
-	// Calculate the filler value.
-	value = 0;
-	bitmask = (1 << bitdepth) - 1;
-	for (i = 0; i < pixels_per_byte; i++) {
-		value |= (filleridx & bitmask) << (i * bitdepth);
+	if (direct_to_vera) {
+		if (compress) {
+			RAM_BANK = 1;
+			image_start = BANK_RAM;
+			memory_decompress(image_start, &VERA.data0);
+			DEBUG_PORT1 = 0;
+		} else {
+			do {
+				bytes_read = cx16_k_macptr(0, false, &VERA.data0);
+			} while (bytes_read > 0);
 		}
+	} else {
 		// Upload the bitmap
 		for (x = 0; VERA.address < vera_max || (vera_max_bank & 0b1) != (VERA.address_hi & 0b1);) {
 			tmp = ((((uint32_t)VERA.address) + ((uint32_t)(VERA.address_hi & 0b1) << 16)));
 			x = (tmp % (uint32_t)(vera_w/pixels_per_byte))*pixels_per_byte;
 			y = tmp / (uint32_t)(vera_w/pixels_per_byte);
-		#if 0
-		vera_adr_bak = VERA.address;
-		vera_adr_h_bak = VERA.address_hi;
-		printf("Y: %u, X: %u, tmp: %lu,\nvera_w: %u\nvera_adr: %u, vera_adr_h: %s\n", y, x, tmp, vera_w, vera_adr_bak, (vera_adr_h_bak & 1) ? "1" : "0");
-		VERA.address = vera_adr_bak;
-		VERA.address_hi = vera_adr_h_bak;
-		#endif
 			if (y >= height) {
 				break;
 			}
 			if (x < width && y < height) {
+				// Load the image's bytes, up to the bytes per row - the x value in bytes
 				bytes_read = cx16_k_macptr((((width) - x))/pixels_per_byte, false, &VERA.data0);
 			} else {
-			//VERA.data0 = value;
+				// Fill the remaining pixels in the row with the border color using a fast assembly routine
 				tmp = (vera_w-x)/pixels_per_byte;
 				if (tmp >= ((uint32_t)1 << 8)) {
 					fill_vera(0xFF, value);
@@ -188,6 +271,7 @@ int uploadimage(const char *filename) {
 				}
 			}
 		}
+		// Fill the rest of the image with the border color using the same fast assembly routine
 		for (; VERA.address < vera_max || (vera_max_bank & 0b1) != (VERA.address_hi & 0b1);) {
 			tmp = vera_max_32 - (((uint32_t)VERA.address) | ((uint32_t)(VERA.address_hi & 0b1) << 16));
 			if (tmp >= ((uint32_t)1 << 8)) {
@@ -196,9 +280,12 @@ int uploadimage(const char *filename) {
 				fill_vera(tmp, value);
 			}
 		}
+	}
+	// Set up the VERA to display the bitmap
 	upload_palette(palette);
 	updatescale();
 	vera_layer_enable(0b11);
+	// Close the file
 	cbm_k_clrch();
 	cbm_k_close(2);
 	return 0;

src/memory_decompress.h

@@ -0,0 +1,6 @@
+#ifndef MEMORY_DECOMPRESS_H
+#define MEMORY_DECOMPRESS_H
+
+extern void * __cdecl__ memory_decompress(const void *input, void *output);
+
+#endif

src/memory_decompress.s

@@ -0,0 +1,19 @@
+.export _memory_decompress
+.import popax
+r0  := $02
+r0l := $02
+r0h := $03
+r1l := $04
+r1h := $05
+.segment "CODE"
+_memory_decompress:
+	jsr popax
+	sta r1l
+	stx r1h
+	jsr popax
+	sta r0l
+	stx r0h
+	jsr $FEED
+	lda r1l
+	ldx r1h
+	rts