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Ensure seeks and reads are within bounds of the track length

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In the previous code, if the game attempted to seek beyond the track
length, or if a "seek & read" would add up to going beyond the
end-of-the-track, the code would pass those requests to the underlying
codecs to handle (and reject with a corresponding error code).

This PR moves those checks up into the CDROM CD-DA code, and will
short-circuit them. Illegal seeks won't be attempted, however the usual
negative return code will still be passed to the game just like before.
Likewise, reads beyond the end will be pruned so they will get as much
audio as possible, without asking the codec for extra.
This commit is contained in:
krcroft 2020-03-31 17:08:27 -07:00 • committed by Patryk Obara
parent 68a1291bc6
commit e8ac2d60f3
2 changed files with 105 additions and 38 deletions
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8
src/dos/cdrom.h
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@ -53,6 +53,7 @@
#define MAX_REDBOOK_TRACKS 99u // a CD can contain 99 playable tracks plus the remaining leadout
#define MIN_REDBOOK_TRACKS 2u // One track plus the lead-out track
#define REDBOOK_PCM_BYTES_PER_MS 176.4f // 44.1 frames/ms * 4 bytes/frame
#define REDBOOK_PCM_BYTES_PER_MIN 10584000u // 44.1 frames/ms * 4 bytes/frame * 1000 ms/s * 60 s/min
#define BYTES_PER_REDBOOK_PCM_FRAME 4u // 2 bytes/sample * 2 samples/frame
#define MAX_REDBOOK_BYTES (MAX_REDBOOK_FRAMES * BYTES_PER_RAW_REDBOOK_FRAME) // length of a CDROM in bytes
#define MAX_REDBOOK_DURATION_MS (99 * 60 * 1000) // 99 minute CDROM in milliseconds
@ -138,6 +139,11 @@ private:
class TrackFile {
protected:
TrackFile(Bit16u _chunkSize) : chunkSize(_chunkSize) {}
bool offsetInsideTrack(const uint32_t offset);
uint32_t adjustOverRead(const uint32_t offset,
const uint32_t requested_bytes);
int length_redbook_bytes = -1;
public:
virtual ~TrackFile() = default;
virtual bool read(uint8_t *buffer,
@ -149,7 +155,7 @@ private:
virtual Bit32u getRate() = 0;
virtual Bit8u getChannels() = 0;
virtual int getLength() = 0;
const Bit16u chunkSize;
const Bit16u chunkSize = 0;
};
class BinaryFile : public TrackFile {