wehub-resource-sync
254 lines
8.1 KiB
C
254 lines
8.1 KiB
C
/*
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* SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/******************************************************************************
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*
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* Utility functions to help build and parse MPEG-2, 4 AAC (M24) Codec
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* Information Element per Bluetooth A2DP specification (Media Codec Capabilities).
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*
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* Layout of Media Codec Capability (starting at LOSC octet):
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* Octet 0: LOSC = 8 (number of octets following LOSC: media type + codec type + 6 CIE)
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* Octet 1: Media type (Audio = 0x00)
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* Octet 2: Media codec type (MPEG-2,4 AAC = 0x02)
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* Octets 3-8: Codec Specific Information Element (6 octets)
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*
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******************************************************************************/
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#include <string.h>
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#include "common/bt_defs.h"
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#include "common/bt_target.h"
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#include "stack/a2d_api.h"
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#include "stack/a2d_m24.h"
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#include "a2d_int.h"
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#if (defined(A2D_AV_CODEC_AAC_INCLUDED) && A2D_AV_CODEC_AAC_INCLUDED == TRUE)
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/******************************************************************************
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** Local helpers
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******************************************************************************/
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/* Count how many bits are set in the lower nibble (used for 4-bit freq2 field). */
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static UINT8 m24_count_bits_4(UINT8 v)
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{
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UINT8 c = 0;
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UINT8 i;
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v &= 0x0F;
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for (i = 0; i < 4; i++) {
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if (v & (1U << i)) {
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c++;
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}
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}
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return c;
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}
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/* Total number of set bits in one byte. */
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static UINT8 m24_popcount8(UINT8 v)
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{
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UINT8 c = 0;
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UINT8 i;
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for (i = 0; i < 8; i++) {
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if (v & (1U << i)) {
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c++;
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}
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}
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return c;
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}
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static tA2D_STATUS m24_validate_ie_for_build(const tA2D_M24_CIE *p_ie)
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{
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if (p_ie == NULL) {
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return A2D_INVALID_PARAMS;
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}
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/* Object type uses b7-b1; b0 is carried in drc */
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if ((p_ie->obj_type & ~A2D_M24_IE_OBJ_TYPE_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->drc & ~A2D_M24_IE_DRC_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->samp_freq1 & ~A2D_M24_IE_SAMP_FREQ1_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->samp_freq2 & ~A2D_M24_IE_SAMP_FREQ2_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->ch & ~A2D_M24_IE_CH_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->vbr & ~A2D_M24_IE_VBR_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->br1 & ~A2D_M24_IE_BR1_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->br2 & ~A2D_M24_IE_BR2_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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if ((p_ie->br3 & ~A2D_M24_IE_BR3_MSK) != 0) {
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return A2D_INVALID_PARAMS;
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}
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/* Capabilities must select at least one object type (bits b7-b1). */
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if ((p_ie->obj_type & A2D_M24_IE_OBJ_TYPE_MSK) == 0) {
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return A2D_INVALID_PARAMS;
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}
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/* At least one sampling frequency (12 bits across two octets) and one channel mode. */
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if (m24_popcount8(p_ie->samp_freq1) + m24_count_bits_4(((p_ie->samp_freq2 & A2D_M24_IE_SAMP_FREQ2_MSK) >> 4)) < 1) {
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return A2D_INVALID_PARAMS;
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}
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if (m24_count_bits_4(p_ie->ch & A2D_M24_IE_CH_MSK) < 1) {
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return A2D_INVALID_PARAMS;
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}
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return A2D_SUCCESS;
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}
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/******************************************************************************
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**
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** Function A2D_BldM24Info
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**
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** Description This function is called by an application to build
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** the M24 Media Codec Capabilities byte sequence
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** beginning from the LOSC octet.
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** Input Parameters:
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** media_type: Indicates Audio, or Multimedia.
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**
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** p_ie: The M24 Codec Information Element information.
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**
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** Output Parameters:
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** p_result: the resulting codec info byte sequence.
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**
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** Returns A2D_SUCCESS if function execution succeeded.
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** Error status code, otherwise.
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******************************************************************************/
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tA2D_STATUS A2D_BldM24Info(UINT8 media_type, tA2D_M24_CIE *p_ie, UINT8 *p_result)
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{
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tA2D_STATUS status;
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if (p_ie == NULL || p_result == NULL) {
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return A2D_INVALID_PARAMS;
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}
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status = m24_validate_ie_for_build(p_ie);
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if (status != A2D_SUCCESS) {
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return status;
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}
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*p_result++ = A2D_M24_INFO_LEN;
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*p_result++ = media_type;
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*p_result++ = A2D_MEDIA_CT_M24;
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/* Codec Specific Information Element (6 octets), A2DP spec */
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*p_result++ = (p_ie->obj_type & A2D_M24_IE_OBJ_TYPE_MSK) | (p_ie->drc & A2D_M24_IE_DRC_MSK);
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*p_result++ = p_ie->samp_freq1 & A2D_M24_IE_SAMP_FREQ1_MSK;
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*p_result++ = (p_ie->samp_freq2 & A2D_M24_IE_SAMP_FREQ2_MSK) | (p_ie->ch & A2D_M24_IE_CH_MSK);
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*p_result++ = (p_ie->vbr & A2D_M24_IE_VBR_MSK) | (p_ie->br1 & A2D_M24_IE_BR1_MSK);
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*p_result++ = p_ie->br2 & A2D_M24_IE_BR2_MSK;
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*p_result = p_ie->br3 & A2D_M24_IE_BR3_MSK;
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return A2D_SUCCESS;
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}
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/******************************************************************************
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**
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** Function A2D_ParsM24Info
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**
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** Description This function is called by an application to parse
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** the M24 Media Codec Capabilities byte sequence
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** beginning from the LOSC octet.
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** Input Parameters:
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** p_info: the byte sequence to parse.
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**
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** for_caps: TRUE, if the byte sequence is for get capabilities response.
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**
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** Output Parameters:
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** p_ie: The M24 Codec Information Element information.
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**
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** Returns A2D_SUCCESS if function execution succeeded.
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** Error status code, otherwise.
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******************************************************************************/
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tA2D_STATUS A2D_ParsM24Info(tA2D_M24_CIE *p_ie, UINT8 *p_info, BOOLEAN for_caps)
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{
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tA2D_STATUS status = A2D_SUCCESS;
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UINT8 losc;
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UINT8 media_type;
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UINT8 cie[6];
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UINT8 i;
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UINT8 sf2_hi;
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UINT8 freq_bits_total;
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UINT8 ch_bits;
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if (p_ie == NULL || p_info == NULL) {
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return A2D_INVALID_PARAMS;
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}
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memset(p_ie, 0, sizeof(tA2D_M24_CIE));
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losc = *p_info++;
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media_type = *p_info++;
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if (losc != A2D_M24_INFO_LEN || media_type != A2D_MEDIA_TYPE_AUDIO || *p_info != A2D_MEDIA_CT_M24) {
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return A2D_WRONG_CODEC;
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}
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p_info++; /* skip media codec type */
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for (i = 0; i < A2D_M24_CIE_LEN; i++) {
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cie[i] = *p_info++;
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}
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/* Unpack CIE */
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p_ie->drc = cie[0] & A2D_M24_IE_DRC_MSK;
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p_ie->obj_type = cie[0] & A2D_M24_IE_OBJ_TYPE_MSK;
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p_ie->samp_freq1 = cie[1] & A2D_M24_IE_SAMP_FREQ1_MSK;
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p_ie->samp_freq2 = cie[2] & A2D_M24_IE_SAMP_FREQ2_MSK;
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p_ie->ch = cie[2] & A2D_M24_IE_CH_MSK;
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p_ie->vbr = cie[3] & A2D_M24_IE_VBR_MSK;
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p_ie->br1 = cie[3] & A2D_M24_IE_BR1_MSK;
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p_ie->br2 = cie[4] & A2D_M24_IE_BR2_MSK;
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p_ie->br3 = cie[5] & A2D_M24_IE_BR3_MSK;
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if (for_caps) {
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/* Get capabilities: need at least one object type and one frequency / channel bit. */
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if ((p_ie->obj_type & A2D_M24_IE_OBJ_TYPE_MSK) == 0) {
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status = A2D_BAD_OBJ_TYPE;
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} else {
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sf2_hi = p_ie->samp_freq2 >> 4;
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freq_bits_total = m24_popcount8(p_ie->samp_freq1) + m24_count_bits_4(sf2_hi);
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ch_bits = m24_count_bits_4(p_ie->ch);
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if (freq_bits_total < 1) {
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status = A2D_NS_SAMP_FREQ;
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} else if (ch_bits < 1) {
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status = A2D_NS_CHANNEL;
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}
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}
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} else {
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/* Stream configuration: single choice for object type, frequency, channels. */
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if (A2D_BitsSet(p_ie->obj_type) != A2D_SET_ONE_BIT) {
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status = A2D_BAD_OBJ_TYPE;
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} else {
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sf2_hi = p_ie->samp_freq2 >> 4;
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freq_bits_total = m24_popcount8(p_ie->samp_freq1) + m24_count_bits_4(sf2_hi);
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if (freq_bits_total != 1) {
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status = A2D_BAD_SAMP_FREQ;
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} else if (A2D_BitsSet(p_ie->ch) != A2D_SET_ONE_BIT) {
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status = A2D_BAD_CHANNEL;
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}
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}
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}
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return status;
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}
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#endif /* #if (defined(A2D_AV_CODEC_AAC_INCLUDED) && A2D_AV_CODEC_AAC_INCLUDED == TRUE) */
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