Add --decompress switch.

cli/cli.cpp

@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <algorithm>
 #include <vector>
 #include <string>
 #include "../src/compress.h"
@@ -20,6 +21,7 @@ void show_help(const char *arg0) {
 	fprintf(stderr, "   --quiet         Suppress status output\n");
 	fprintf(stderr, "   --crc           Log CRC32 checksums, ignore output files and methods\n");
 	fprintf(stderr, "   --fast          Use only basic zlib or lz4 for fastest result\n");
+	fprintf(stderr, "   --decompress    Write out to raw ISO, decompressing as needed\n");
 	fprintf(stderr, "   --block=N       Specify a block size (default is 2048)\n");
 	fprintf(stderr, "                   Most readers only support the 2048 size\n");
 	fprintf(stderr, "   --format=VER    Specify cso version (options: cso1, cso2, zso)\n");
@@ -105,6 +107,7 @@ struct Arguments {
 	bool smallest;
 	bool quiet;
 	bool crc;
+	bool decompress;
 };
 
 void default_args(Arguments &args) {
@@ -124,6 +127,7 @@ void default_args(Arguments &args) {
 	args.smallest = false;
 	args.quiet = false;
 	args.crc = false;
+	args.decompress = false;
 }
 
 int parse_args(Arguments &args, int argc, char *argv[]) {
@@ -166,6 +170,8 @@ int parse_args(Arguments &args, int argc, char *argv[]) {
 				args.fast = true;
 			} else if (has_arg(i, argv, "--smallest")) {
 				args.smallest = true;
+			} else if (has_arg(i, argv, "--decompress")) {
+				args.decompress = true;
 			} else if (has_arg_method(i, argv, "--use-", method)) {
 				args.flags_use |= method;
 			} else if (has_arg_method(i, argv, "--no-", method)) {
@@ -220,9 +226,13 @@ int validate_args(const char *arg0, Arguments &args) {
 				continue;
 			}
 
-			const std::string ext = args.inputs[i].substr(args.inputs[i].size() - 4);
-			if (ext == ".iso" || ext == ".ISO") {
+			std::string ext = args.inputs[i].substr(args.inputs[i].size() - 4);
+			std::transform(ext.begin(), ext.end(), ext.begin(), ::tolower);
+
+			if (!args.decompress && ext == ".iso") {
 				args.outputs.push_back(args.inputs[i].substr(0, args.inputs[i].size() - 4) + ".cso");
+			} else if (args.decompress && (ext == ".cso" || ext == ".zso")) {
+				args.outputs.push_back(args.inputs[i].substr(0, args.inputs[i].size() - 4) + ".iso");
 			}
 		}
 
@@ -266,6 +276,9 @@ int validate_args(const char *arg0, Arguments &args) {
 	if (args.smallest) {
 		args.flags_final |= maxcso::TASKFLAG_FORCE_ALL;
 	}
+	if (args.decompress) {
+		args.flags_final |= maxcso::TASKFLAG_DECOMPRESS;
+	}
 	args.flags_final |= args.flags_fmt;
 
 	return 0;

src/compress.cpp

@@ -12,6 +12,7 @@ namespace maxcso {
 // Anything above this is insane.  This value is even insane.
 static const uint32_t MAX_BLOCK_SIZE = 0x40000;
 
+// This actually handles decompression too.  They're basically the same.
 class CompressionTask {
 public:
 	CompressionTask(uv_loop_t *loop, const Task &t)

src/compress.h

@@ -7,7 +7,7 @@
 
 namespace maxcso {
 
-static const char *VERSION = "1.4.6";
+static const char *VERSION = "1.5.0";
 
 struct Task;
 
@@ -43,6 +43,8 @@ enum TaskFlags {
 	TASKFLAG_NO_LZ4_HC_BRUTE = 0x200,
 
 	TASKFLAG_NO_ALL = TASKFLAG_NO_ZLIB | TASKFLAG_NO_ZOPFLI | TASKFLAG_NO_7ZIP | TASKFLAG_NO_LZ4,
+
+	TASKFLAG_DECOMPRESS = 0x400,
 };
 
 typedef std::function<void (const Task *, TaskStatus status, int64_t pos, int64_t total, int64_t written)> ProgressCallback;

src/output.cpp

@@ -47,8 +47,14 @@ void Output::SetFile(uv_file file, int64_t srcSize, uint32_t blockSize, CSOForma
 	const uint32_t sectors = static_cast<uint32_t>((srcSize + blockSize_ - 1) >> blockShift_);
 	// Start after the header and index, which we'll fill in later.
 	index_ = new uint32_t[sectors + 1];
-	// Start after the end of the index data and header.
-	dstPos_ = sizeof(CSOHeader) + (sectors + 1) * sizeof(uint32_t);
+	if (flags_ & TASKFLAG_DECOMPRESS) {
+		// Decompressing, so no header.
+		// We still track the index for code simplicity, but throw it away.
+		dstPos_ = 0;
+	} else {
+		// Start after the end of the index data and header.
+		dstPos_ = sizeof(CSOHeader) + (sectors + 1) * sizeof(uint32_t);
+	}
 
 	// TODO: We might be able to optimize shift better by running through the data.
 	// That would require either a second pass or keeping the entire result in RAM.
@@ -266,6 +272,9 @@ void Output::HandleReadySector(Sector *sector) {
 }
 
 bool Output::ShouldCompress(int64_t pos, uint8_t *buffer) {
+	if (flags_ & TASKFLAG_DECOMPRESS) {
+		return false;
+	}
 	if (flags_ & TASKFLAG_FORCE_ALL) {
 		return true;
 	}
@@ -299,6 +308,13 @@ void Output::Flush() {
 		return;
 	}
 
+	if (flags_ & TASKFLAG_DECOMPRESS) {
+		// Okay, we're done.  No header or index to write when decompressing.
+		state_ |= STATE_INDEX_WRITTEN;
+		CheckFinish();
+		return;
+	}
+
 	CSOHeader *header = new CSOHeader;
 	if (fmt_ == CSO_FMT_ZSO) {
 		memcpy(header->magic, ZSO_MAGIC, sizeof(header->magic));