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esp-idf/components/bt/bluedroid/stack/a2dp/a2d_sbc.c

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/******************************************************************************
*
* Copyright (C) 2002-2012 Broadcom Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************/
/******************************************************************************
*
* Utility functions to help build and parse SBC Codec Information Element
* and Media Payload.
*
******************************************************************************/
#include "bt_target.h"
#include <string.h>
#include "a2d_api.h"
#include "a2d_int.h"
#include "a2d_sbc.h"
#include "bt_utils.h"
/*************************************************************************************************
* SBC descramble code
* Purpose: to tie the SBC code with BTE/mobile stack code,
* especially for the case when the SBC is ported into a third-party Multimedia chip
*
* Algorithm:
* init process: all counters reset to 0,
* calculate base_index: (6 + s16NumOfChannels*s16NumOfSubBands/2)
* scramble side: the init process happens every time SBC_Encoder_Init() is called.
* descramble side: it would be nice to know if he "init" process has happened.
* alter the SBC SYNC word 0x9C (1001 1100) to 0x8C (1000 1100).
*
* scramble process:
* The CRC byte:
* Every SBC frame has a frame header.
* The 1st byte is the sync word and the following 2 bytes are about the stream format.
* They are supposed to be "constant" within a "song"
* The 4th byte is the CRC byte. The CRC byte is bound to be random.
* Derive 2 items from the CRC byte; one is the "use" bit, the other is the "index".
*
* SBC keeps 2 sets of "use" & "index"; derived the current and the previous frame.
*
* The "use" bit is any bit in SBC_PRTC_USE_MASK is set.
* If set, SBC uses the "index" from the current frame.
* If not set, SBC uses the "index" from the previous frame or 0.
*
* index = (CRC & 0x3) + ((CRC & 0x30) >> 2) // 8 is the max index
*
* if(index > 0)
* {
* p = &u8frame[base_index];
* if((index&1)&&(u16PacketLength > (base_index+index*2)))
* {
* // odd index: swap 2 bytes
* tmp = p[index];
* p[index] = p[index*2];
* p[index*2] = tmp;
* }
* else
* {
* // even index: shift by 3
* tmp = (p[index] >> 3) + (p[index] << 5);
* p[index] = tmp;
* }
* }
* //else index is 0. The frame stays unaltered
*
*/
#define A2D_SBC_SYNC_WORD 0x9C
#define A2D_SBC_CRC_IDX 3
#define A2D_SBC_USE_MASK 0x64
#define A2D_SBC_SYNC_MASK 0x10
#define A2D_SBC_CIDX 0
#define A2D_SBC_LIDX 1
#define A2D_SBC_CH_M_BITS 0xC /* channel mode bits: 0: mono; 1 ch */
#define A2D_SBC_SUBBAND_BIT 0x1 /* num of subband bit: 0:4; 1: 8 */
#define A2D_SBC_GET_IDX(sc) (((sc) & 0x3) + (((sc) & 0x30) >> 2))
typedef struct
{
UINT8 use;
UINT8 idx;
} tA2D_SBC_FR_CB;
typedef struct
{
tA2D_SBC_FR_CB fr[2];
UINT8 index;
UINT8 base;
} tA2D_SBC_DS_CB;
static tA2D_SBC_DS_CB a2d_sbc_ds_cb;
/*int a2d_count = 0;*/
/******************************************************************************
**
** Function A2D_SbcChkFrInit
**
** Description check if need to init the descramble control block.
**
** Returns nothing.
******************************************************************************/
void A2D_SbcChkFrInit(UINT8 *p_pkt)
{
UINT8 fmt;
UINT8 num_chnl = 1;
UINT8 num_subband = 4;
if((p_pkt[0] & A2D_SBC_SYNC_MASK) == 0)
{
a2d_cb.use_desc = TRUE;
fmt = p_pkt[1];
p_pkt[0] |= A2D_SBC_SYNC_MASK;
memset(&a2d_sbc_ds_cb, 0, sizeof(tA2D_SBC_DS_CB));
if(fmt & A2D_SBC_CH_M_BITS)
num_chnl = 2;
if(fmt & A2D_SBC_SUBBAND_BIT)
num_subband = 8;
a2d_sbc_ds_cb.base = 6 + num_chnl*num_subband/2;
/*printf("base: %d\n", a2d_sbc_ds_cb.base);
a2d_count = 0;*/
}
}
/******************************************************************************
**
** Function A2D_SbcDescramble
**
** Description descramble the packet.
**
** Returns nothing.
******************************************************************************/
void A2D_SbcDescramble(UINT8 *p_pkt, UINT16 len)
{
tA2D_SBC_FR_CB *p_cur, *p_last;
UINT32 idx, tmp, tmp2;
if(a2d_cb.use_desc)
{
/* c2l */
p_last = &a2d_sbc_ds_cb.fr[A2D_SBC_LIDX];
p_cur = &a2d_sbc_ds_cb.fr[A2D_SBC_CIDX];
p_last->idx = p_cur->idx;
p_last->use = p_cur->use;
/* getc */
p_cur->use = p_pkt[A2D_SBC_CRC_IDX] & A2D_SBC_USE_MASK;
p_cur->idx = A2D_SBC_GET_IDX(p_pkt[A2D_SBC_CRC_IDX]);
a2d_sbc_ds_cb.index = (p_cur->use)?A2D_SBC_CIDX:A2D_SBC_LIDX;
/*
printf("%05d: ar[%02d]: x%02x, msk: x%02x, use: %s, idx: %02d, ",
a2d_count++,
A2D_SBC_CRC_IDX, p_pkt[A2D_SBC_CRC_IDX], A2D_SBC_USE_MASK,
(p_cur->use)?"cur":"lst", p_cur->idx);
*/
/* descramble */
idx = a2d_sbc_ds_cb.fr[a2d_sbc_ds_cb.index].idx;
if(idx > 0)
{
p_pkt = &p_pkt[a2d_sbc_ds_cb.base];
if((idx&1) && (len > (a2d_sbc_ds_cb.base+(idx<<1))))
{
tmp2 = (idx<<1);
tmp = p_pkt[idx];
p_pkt[idx] = p_pkt[tmp2];
p_pkt[tmp2] = tmp;
/*
printf("tmp2: %02d, len: %d, idx: %d\n",
tmp2, len, a2d_sbc_ds_cb.fr[a2d_sbc_ds_cb.index].idx);
*/
}
else
{
tmp2 = p_pkt[idx];
tmp = (tmp2>>3)+(tmp2<<5);
p_pkt[idx] = (UINT8)tmp;
/*
printf("tmp: x%02x, len: %d, idx: %d(cmp:%d)\n",
(UINT8)tmp2, len, a2d_sbc_ds_cb.fr[a2d_sbc_ds_cb.index].idx,
(a2d_sbc_ds_cb.base+(idx<<1)));
*/
}
}
/*
else
{
printf("!!!!\n");
}
*/
}
}
/******************************************************************************
**
** Function A2D_BldSbcInfo
**
** Description This function is called by an application to build
** the SBC Media Codec Capabilities byte sequence
** beginning from the LOSC octet.
** Input Parameters:
** media_type: Indicates Audio, or Multimedia.
**
** p_ie: The SBC Codec Information Element information.
**
** Output Parameters:
** p_result: the resulting codec info byte sequence.
**
** Returns A2D_SUCCESS if function execution succeeded.
** Error status code, otherwise.
******************************************************************************/
tA2D_STATUS A2D_BldSbcInfo(UINT8 media_type, tA2D_SBC_CIE *p_ie, UINT8 *p_result)
{
tA2D_STATUS status;
if( p_ie == NULL || p_result == NULL ||
(p_ie->samp_freq & ~A2D_SBC_IE_SAMP_FREQ_MSK) ||
(p_ie->ch_mode & ~A2D_SBC_IE_CH_MD_MSK) ||
(p_ie->block_len & ~A2D_SBC_IE_BLOCKS_MSK) ||
(p_ie->num_subbands & ~A2D_SBC_IE_SUBBAND_MSK) ||
(p_ie->alloc_mthd & ~A2D_SBC_IE_ALLOC_MD_MSK) ||
(p_ie->max_bitpool < p_ie->min_bitpool) ||
(p_ie->max_bitpool < A2D_SBC_IE_MIN_BITPOOL) ||
(p_ie->max_bitpool > A2D_SBC_IE_MAX_BITPOOL) ||
(p_ie->min_bitpool < A2D_SBC_IE_MIN_BITPOOL) ||
(p_ie->min_bitpool > A2D_SBC_IE_MAX_BITPOOL) )
{
/* if any unused bit is set */
status = A2D_INVALID_PARAMS;
}
else
{
status = A2D_SUCCESS;
*p_result++ = A2D_SBC_INFO_LEN;
*p_result++ = media_type;
*p_result++ = A2D_MEDIA_CT_SBC;
/* Media Codec Specific Information Element */
*p_result++ = p_ie->samp_freq | p_ie->ch_mode;
*p_result++ = p_ie->block_len | p_ie->num_subbands | p_ie->alloc_mthd;
*p_result++ = p_ie->min_bitpool;
*p_result = p_ie->max_bitpool;
}
return status;
}
/******************************************************************************
**
** Function A2D_ParsSbcInfo
**
** Description This function is called by an application to parse
** the SBC Media Codec Capabilities byte sequence
** beginning from the LOSC octet.
** Input Parameters:
** p_info: the byte sequence to parse.
**
** for_caps: TRUE, if the byte sequence is for get capabilities response.
**
** Output Parameters:
** p_ie: The SBC Codec Information Element information.
**
** Returns A2D_SUCCESS if function execution succeeded.
** Error status code, otherwise.
******************************************************************************/
tA2D_STATUS A2D_ParsSbcInfo(tA2D_SBC_CIE *p_ie, UINT8 *p_info, BOOLEAN for_caps)
{
tA2D_STATUS status;
UINT8 losc;
if( p_ie == NULL || p_info == NULL)
status = A2D_INVALID_PARAMS;
else
{
losc = *p_info++;
p_info++;
/* If the function is called for the wrong Media Type or Media Codec Type */
if(losc != A2D_SBC_INFO_LEN || *p_info != A2D_MEDIA_CT_SBC)
status = A2D_WRONG_CODEC;
else
{
p_info++;
p_ie->samp_freq = *p_info & A2D_SBC_IE_SAMP_FREQ_MSK;
p_ie->ch_mode = *p_info & A2D_SBC_IE_CH_MD_MSK;
p_info++;
p_ie->block_len = *p_info & A2D_SBC_IE_BLOCKS_MSK;
p_ie->num_subbands = *p_info & A2D_SBC_IE_SUBBAND_MSK;
p_ie->alloc_mthd = *p_info & A2D_SBC_IE_ALLOC_MD_MSK;
p_info++;
p_ie->min_bitpool = *p_info++;
p_ie->max_bitpool = *p_info;
status = A2D_SUCCESS;
if(p_ie->min_bitpool < A2D_SBC_IE_MIN_BITPOOL || p_ie->min_bitpool > A2D_SBC_IE_MAX_BITPOOL )
status = A2D_BAD_MIN_BITPOOL;
if(p_ie->max_bitpool < A2D_SBC_IE_MIN_BITPOOL || p_ie->max_bitpool > A2D_SBC_IE_MAX_BITPOOL ||
p_ie->max_bitpool < p_ie->min_bitpool)
status = A2D_BAD_MAX_BITPOOL;
if(for_caps == FALSE)
{
if(A2D_BitsSet(p_ie->samp_freq) != A2D_SET_ONE_BIT)
status = A2D_BAD_SAMP_FREQ;
if(A2D_BitsSet(p_ie->ch_mode) != A2D_SET_ONE_BIT)
status = A2D_BAD_CH_MODE;
if(A2D_BitsSet(p_ie->block_len) != A2D_SET_ONE_BIT)
status = A2D_BAD_BLOCK_LEN;
if(A2D_BitsSet(p_ie->num_subbands) != A2D_SET_ONE_BIT)
status = A2D_BAD_SUBBANDS;
if(A2D_BitsSet(p_ie->alloc_mthd) != A2D_SET_ONE_BIT)
status = A2D_BAD_ALLOC_MTHD;
}
}
}
return status;
}
/******************************************************************************
**
** Function A2D_BldSbcMplHdr
**
** Description This function is called by an application to parse
** the SBC Media Payload header.
** Input Parameters:
** frag: 1, if fragmented. 0, otherwise.
**
** start: 1, if the starting packet of a fragmented frame.
**
** last: 1, if the last packet of a fragmented frame.
**
** num: If frag is 1, this is the number of remaining fragments
** (including this fragment) of this frame.
** If frag is 0, this is the number of frames in this packet.
**
** Output Parameters:
** p_dst: the resulting media payload header byte sequence.
**
** Returns void.
******************************************************************************/
void A2D_BldSbcMplHdr(UINT8 *p_dst, BOOLEAN frag, BOOLEAN start, BOOLEAN last, UINT8 num)
{
if(p_dst)
{
*p_dst = 0;
if(frag)
*p_dst |= A2D_SBC_HDR_F_MSK;
if(start)
*p_dst |= A2D_SBC_HDR_S_MSK;
if(last)
*p_dst |= A2D_SBC_HDR_L_MSK;
*p_dst |= (A2D_SBC_HDR_NUM_MSK & num);
}
}
/******************************************************************************
**
** Function A2D_ParsSbcMplHdr
**
** Description This function is called by an application to parse
** the SBC Media Payload header.
** Input Parameters:
** p_src: the byte sequence to parse..
**
** Output Parameters:
** frag: 1, if fragmented. 0, otherwise.
**
** start: 1, if the starting packet of a fragmented frame.
**
** last: 1, if the last packet of a fragmented frame.
**
** num: If frag is 1, this is the number of remaining fragments
** (including this fragment) of this frame.
** If frag is 0, this is the number of frames in this packet.
**
** Returns void.
******************************************************************************/
void A2D_ParsSbcMplHdr(UINT8 *p_src, BOOLEAN *p_frag, BOOLEAN *p_start, BOOLEAN *p_last, UINT8 *p_num)
{
if(p_src && p_frag && p_start && p_last && p_num)
{
*p_frag = (*p_src & A2D_SBC_HDR_F_MSK) ? TRUE: FALSE;
*p_start= (*p_src & A2D_SBC_HDR_S_MSK) ? TRUE: FALSE;
*p_last = (*p_src & A2D_SBC_HDR_L_MSK) ? TRUE: FALSE;
*p_num = (*p_src & A2D_SBC_HDR_NUM_MSK);
}
}
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