1501c2bf3e
ready for testing. Also the documentation is far from complete (it's in it's early phases). Unfortunately I don't have enough experience in hardware programming to prototype it first, so I'll be testing the things that I design in the document. git-svn-id: file:///srv/svn/repos/haiku/trunk/current@4275 a95241bf-73f2-0310-859d-f6bbb57e9c96
92 lines
2.3 KiB
C
92 lines
2.3 KiB
C
/*
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** USB_rle.h
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**
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** Copyright 1999, Be Incorporated. All Rights Reserved.
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**
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*/
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#ifndef _USB_RLE_H
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#define _USB_RLE_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct _usbd_param_hdr;
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/*
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Run Length encoding records for isochronous IN transfers.
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Run Length encoding records are used to identify which samples in
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the buffer are good which are bad and which are missing.
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Bad bytes are not extracted from the buffer, but are padded to next
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nearest sample boundary. The ultimate consumer of the buffer
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should also receive the RLE array.
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RLE records are constructed based on the following rules:
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1. an RLE record contains a sample count and a status
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(good, bad, missing or unknown). A buffer has
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associated with it an array of rle records. The number of
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rle records available is specified in the RLE header. The
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number used is also in the RLE header.
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2. Within the scope of a buffer, successive packets with the
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same completion status are represented with (1) rle record.
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For example, after three transactions which have completion
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status of success, the byte count in the rle record for this
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position in the data stream represents the bytes received in
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all three packets.
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3. New rle records are initialized each time the status for a
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given packet differs from that of the previous packet.
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*/
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#define RLE_GOOD 1
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#define RLE_BAD 2
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#define RLE_MISSING 3
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#define RLE_UNKNOWN 4
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/*
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Name: rle
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Purpose: used to represent the state of a portion of a data buffer
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Fields:
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rle_status will contain only the values: RLE_GOOD, RLE_BAD, RLE_MISSING
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sample_count the number of usb samples in the buffer associated with this rle
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record.
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Notes:
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If the buffer length field in queue_buffer_single structure changes to an
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uint32 from uin16, then the sample_count data type must
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track this change.
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*/
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typedef struct rle {
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uint16 rle_status;
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uint16 sample_count;
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} rle;
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/*
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Name: rlea
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Purpose: used as the primary rle information data structure between the
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USB driver stack and a consuming client.
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Fields:
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length the number of rle records available in this structure.
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num_valid filled in by the USB driver. indicates the number of valid
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records filled.
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rles[] unconstrained array of rle records.
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*/
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typedef struct rlea {
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uint16 length;
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uint16 num_valid;
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rle rles[1];
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} rlea;
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#ifdef __cplusplus
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}
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#endif
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#endif
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