flycast/core/imgread/chd.cpp

#include "common.h"
#include "stdclass.h"

#include <libchdr/chd.h>

/* tracks are padded to a multiple of this many frames */
constexpr uint32_t CD_TRACK_PADDING = 4;

struct CHDDisc : Disc
{
	chd_file *chd = nullptr;
	FILE *fp = nullptr;
	u8* hunk_mem = nullptr;
	u32 old_hunk = 0;

	u32 hunkbytes = 0;
	u32 sph = 0;

	void tryOpen(const char* file);

	~CHDDisc() override
	{
		delete[] hunk_mem;

		if (chd)
			chd_close(chd);
		if (fp)
			std::fclose(fp);
	}
};

struct CHDTrack : TrackFile
{
	CHDDisc* disc;
	u32 StartFAD;
	s32 Offset;
	u32 fmt;
	bool swap_bytes;

	CHDTrack(CHDDisc* disc, u32 StartFAD, s32 Offset, u32 fmt, bool swap_bytes)
	{
		this->disc = disc;
		this->StartFAD = StartFAD;
		this->Offset = Offset;
		this->fmt = fmt;
		this->swap_bytes = swap_bytes;
	}

	bool Read(u32 FAD, u8* dst, SectorFormat* sector_type, u8* subcode, SubcodeFormat* subcode_type) override
	{
		u32 fad_offs = FAD + Offset;
		u32 hunk=(fad_offs)/disc->sph;
		if (disc->old_hunk!=hunk)
		{
			if (chd_read(disc->chd,hunk,disc->hunk_mem) != CHDERR_NONE)
				return false;
			disc->old_hunk = hunk;
		}

		u32 hunk_ofs = fad_offs%disc->sph;

		memcpy(dst, disc->hunk_mem + hunk_ofs * (2352+96), fmt);

		if (swap_bytes)
		{
			for (u32 i = 0; i < fmt; i += 2)
			{
				u8 b = dst[i];
				dst[i] = dst[i + 1];
				dst[i + 1] = b;
			}
		}
		*sector_type=fmt==2352?SECFMT_2352:SECFMT_2048_MODE1;

		//While space is reserved for it, the images contain no actual subcodes
		//memcpy(subcode,disc->hunk_mem+hunk_ofs*(2352+96)+2352,96);
		*subcode_type=SUBFMT_NONE;

		return true;
	}
};

void CHDDisc::tryOpen(const char* file)
{
	fp = nowide::fopen(file, "rb");
	if (fp == nullptr)
		throw FlycastException(std::string("Cannot open CHD file ") + file);

	chd_error err = chd_open_file(fp, CHD_OPEN_READ, 0, &chd);

	if (err != CHDERR_NONE)
		throw FlycastException(std::string("Invalid CHD file ") + file);

	INFO_LOG(GDROM, "chd: parsing file %s", file);

	const chd_header* head = chd_get_header(chd);

	hunkbytes = head->hunkbytes;
	hunk_mem = new u8[hunkbytes];
	old_hunk=0xFFFFFFF;

	sph = hunkbytes/(2352+96);

	if (hunkbytes % (2352 + 96) != 0)
		throw FlycastException(std::string("Invalid hunkbytes for CHD file ") + file);

	u32 tag;
	u8 flags;
	char temp[512];
	u32 temp_len;
	u32 total_frames = 150;

	u32 Offset = 0;

	for(;;)
	{
		char type[16], subtype[16], pgtype[16], pgsub[16];
		int tkid=-1, frames=0, pregap=0, postgap=0, padframes=0;

		err = chd_get_metadata(chd, CDROM_TRACK_METADATA2_TAG, tracks.size(), temp, sizeof(temp), &temp_len, &tag, &flags);
		if (err == CHDERR_NONE)
		{
			//"TRACK:%d TYPE:%s SUBTYPE:%s FRAMES:%d PREGAP:%d PGTYPE:%s PGSUB:%s POSTGAP:%d"
			sscanf(temp, CDROM_TRACK_METADATA2_FORMAT, &tkid, type, subtype, &frames, &pregap, pgtype, pgsub, &postgap);
		}
		else if (CHDERR_NONE== (err = chd_get_metadata(chd, CDROM_TRACK_METADATA_TAG, tracks.size(), temp, sizeof(temp), &temp_len, &tag, &flags)) )
		{
			//CDROM_TRACK_METADATA_FORMAT	"TRACK:%d TYPE:%s SUBTYPE:%s FRAMES:%d"
			sscanf(temp, CDROM_TRACK_METADATA_FORMAT, &tkid, type, subtype, &frames);
		}
		else
		{
			err = chd_get_metadata(chd, GDROM_OLD_METADATA_TAG, tracks.size(), temp, sizeof(temp), &temp_len, &tag, &flags);
			if (err != CHDERR_NONE)
			{
				err = chd_get_metadata(chd, GDROM_TRACK_METADATA_TAG, tracks.size(), temp, sizeof(temp), &temp_len, &tag, &flags);
			}
			if (err == CHDERR_NONE)
			{
				//GDROM_TRACK_METADATA_FORMAT	"TRACK:%d TYPE:%s SUBTYPE:%s FRAMES:%d PAD:%d PREGAP:%d PGTYPE:%s PGSUB:%s POSTGAP:%d"
				sscanf(temp, GDROM_TRACK_METADATA_FORMAT, &tkid, type, subtype, &frames, &padframes, &pregap, pgtype, pgsub, &postgap);
			}
			else
			{
				break;
			}
		}

		if (tkid != (int)tracks.size() + 1
				|| (strcmp(type, "MODE1_RAW") != 0 && strcmp(type, "AUDIO") != 0 && strcmp(type, "MODE1") != 0)
				|| strcmp(subtype, "NONE") != 0
				|| pregap != 0
				|| postgap != 0)
		{
			throw FlycastException((std::string("chd: track type ") + type) + " is not supported");
		}
		DEBUG_LOG(GDROM, "%s", temp);
		Track t;
		t.StartFAD = total_frames;
		total_frames += frames;
		t.EndFAD = total_frames - 1;
		t.CTRL = strcmp(type,"AUDIO") == 0 ? 0 : 4;

		t.file = new CHDTrack(this, t.StartFAD, Offset - t.StartFAD, strcmp(type, "MODE1") ? 2352 : 2048,
							  // audio tracks are byteswapped in CHDv5+
							  t.CTRL == 0 && head->version >= 5);

		// CHD files are padded, so we have to respect the offset
		int padded = (frames + CD_TRACK_PADDING - 1) / CD_TRACK_PADDING;
		Offset += padded * CD_TRACK_PADDING;

		tracks.push_back(t);
	}

	if (total_frames!=549300 || tracks.size()<3)
		WARN_LOG(GDROM, "WARNING: chd: Total frames is wrong: %u frames (549300 expected) in %zu tracks", total_frames, tracks.size());

	FillGDSession();
}


Disc* chd_parse(const char* file, std::vector<u8> *digest)
{
	if (get_file_extension(file) != "chd")
		return nullptr;

	CHDDisc* rv = new CHDDisc();

	try {
		rv->tryOpen(file);
		if (digest != nullptr)
		{
			digest->resize(sizeof(chd_get_header(rv->chd)->sha1));
			memcpy(digest->data(), chd_get_header(rv->chd)->sha1, digest->size());
		}
		return rv;
	} catch (...) {
		delete rv;
		throw;
	}
}