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annotate libtwamr/ietf_fo.c @ 477:4c9222d95647

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libtwamr encoder: always emit frame->mode = mode; In the original implementation of amr_encode_frame(), the 'mode' member of the output struct was set to 0xFF if the output frame type is TX_NO_DATA. This design was made to mimic the mode field (16-bit word) being set to 0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends on this struct member being set in any way, and amr_frame_to_tseq() generates the needed 0xFFFF on its own, based on frame->type being equal to TX_NO_DATA. It is simpler and more efficient to always set frame->mode to the actual encoding mode in amr_encode_frame(), and this new behavior has already been documented in doc/AMR-library-API description in anticipation of the present change.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 18 May 2024 22:30:42 +0000
parents ebe499058c63
children
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441
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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1 /*
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2 * The function implemented in this module groks the first octet of
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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3 * an RFC 4867 payload and tells the calling application how many more
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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4 * bytes need to be read, or if the frame type is invalid.
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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5 */
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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6
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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7 #include <stdint.h>
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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8 #include "tw_amr.h"
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9
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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10 static const uint8_t extra_bytes_per_ft[9] =
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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11 {12, 13, 15, 17, 19, 20, 26, 31, 5};
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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12
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13 int amr_ietf_grok_first_octet(uint8_t fo)
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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14 {
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15 uint8_t ft;
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16
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17 ft = (fo & 0x78) >> 3;
ebe499058c63 libtwamr: implement API functions for RFC 4867 I/O
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18 if (ft == AMR_FT_NODATA)
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19 return 0;
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20 if (ft > MRDTX)
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21 return -1;
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22 return extra_bytes_per_ft[ft];
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23 }