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Add comments to many functions

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master
Mikko Markus Torni 8 years ago
parent af4ac1e764
commit 9c21efe78b
9 changed files with 201 additions and 15 deletions
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18
srslte/lib/fec/cbsegm.c
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@ -48,7 +48,13 @@ const uint32_t tc_cb_sizes[SRSLTE_NOF_TC_CB_SIZES] = { 40, 48, 56, 64, 72, 80, 8
4800, 4864, 4928, 4992, 5056, 5120, 5184, 5248, 5312, 5376, 5440, 5504,
5568, 5632, 5696, 5760, 5824, 5888, 5952, 6016, 6080, 6144 };
/* Calculate Codeblock Segmentation as in Section 5.1.2 of 36.212 */
/**
* Calculate Codeblock Segmentation parameters as in Section 5.1.2 of 36.212
*
* @param[out] s Output of code block segmentation calculation
* @param[in] tbs Input Transport Block Size in bits. CRC's will be added to this
* @return Error code
*/
int srslte_cbsegm(srslte_cbsegm_t *s, uint32_t tbs) {
uint32_t Bp, B, idx1;
int ret;
@ -104,6 +110,8 @@ int srslte_cbsegm(srslte_cbsegm_t *s, uint32_t tbs) {
/*
* Finds index of minimum K>=long_cb in Table 5.1.3-3 of 36.212
*
* @return I_TBS or error code
*/
int srslte_cbsegm_cbindex(uint32_t long_cb) {
int j = 0;
@ -120,6 +128,8 @@ int srslte_cbsegm_cbindex(uint32_t long_cb) {
/*
* Returns Turbo coder interleaver size for Table 5.1.3-3 (36.212) index
*
* @return Code block size in bits or error code
*/
int srslte_cbsegm_cbsize(uint32_t index) {
if (index < SRSLTE_NOF_TC_CB_SIZES) {
@ -129,6 +139,12 @@ int srslte_cbsegm_cbsize(uint32_t index) {
}
}
/**
* Check is code block size is valid for LTE Turbo Code
*
* @param[in] size Size of code block in bits
* @return true if Code Block size is allowed
*/
bool srslte_cbsegm_cbsize_isvalid(uint32_t size) {
for (int i=0;i<SRSLTE_NOF_TC_CB_SIZES;i++) {
if (tc_cb_sizes[i] == size) {

13
srslte/lib/fec/convcoder.c
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@ -33,6 +33,19 @@
#include "srslte/fec/convcoder.h"
#include "parity.h"
/**
* Convolution encodes according to given parameters.
*
* q->R is rate
* q->tail_biting enables tail biting
* q->K is a parameter for tail biting
*
* @param[in] q Convolution coder parameters
* @param[in] input Unpacked bit array. Size frame_length
* @param[out] output Unpacked bit array. Size q->R*frame_length if q->tail_biting, else q->R*(frame_length + q->K - 1)
* @param[in] frame_length Number of bits in input_array
* @return Number of bits in output
*/
int srslte_convcoder_encode(srslte_convcoder_t *q, uint8_t *input, uint8_t *output, uint32_t frame_length) {
uint32_t sr;
uint32_t i,j;

6
srslte/lib/fec/rm_conv.c
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@ -39,6 +39,12 @@ uint8_t RM_PERM_CC_INV[NCOLS] =
{ 16, 0, 24, 8, 20, 4, 28, 12, 18, 2, 26, 10, 22, 6, 30, 14, 17, 1, 25, 9,
21, 5, 29, 13, 19, 3, 27, 11, 23, 7, 31, 15 };
/**
* Rate matching for convolution encoder
*
* @param[in] input Unpacked bit array. Size in_len
* @param[output] output Unpacked bit array. Size out_len <= in_len
*/
int srslte_rm_conv_tx(uint8_t *input, uint32_t in_len, uint8_t *output, uint32_t out_len) {
uint8_t tmp[3 * NCOLS * NROWS_MAX];

23
srslte/lib/fec/rm_turbo.c
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@ -240,6 +240,20 @@ void srslte_rm_turbo_gentables() {
}
/**
* Rate matching for LTE Turbo Coder
*
* @param[out] w_buff Preallocated softbuffer
* @param[in] systematic Input code block in a byte array
* @param[in] parity Input code turbo coder parity bits in a byte array
* @param[out] output Rate matched output array of size out_len
* @param out_len Output buffer size to be filled with as many FEC bits as fit
* @param w_offset Start writing to output at this bit offset
* @param cb_idx Code block index. Used to lookup interleaver parameters
* @param rv_idx Redundancy Version Index. Indexed offset of FEC bits to copy
*
* @return Error code
*/
int srslte_rm_turbo_tx_lut(uint8_t *w_buff, uint8_t *systematic, uint8_t *parity, uint8_t *output,
uint32_t cb_idx, uint32_t out_len,
uint32_t w_offset, uint32_t rv_idx)
@ -284,6 +298,15 @@ int srslte_rm_turbo_tx_lut(uint8_t *w_buff, uint8_t *systematic, uint8_t *parity
}
}
/**
* Undoes rate matching for LTE Turbo Coder. Expands rate matched buffer to full size buffer.
*
* @param[in] input Input buffer of size in_len
* @param[out] output Output buffer of size 3*srslte_cbsegm_cbsize(cb_idx)+12
* @param[in] cb_idx Code block table index
* @param[in] rv_idx Redundancy Version from DCI control message
* @return Error code
*/
int srslte_rm_turbo_rx_lut(int16_t *input, int16_t *output, uint32_t in_len, uint32_t cb_idx, uint32_t rv_idx)
{

24
srslte/lib/phch/pbch.c
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@ -111,6 +111,10 @@ int srslte_pbch_cp(cf_t *input, cf_t *output, srslte_cell_t cell, bool put) {
* Returns the number of symbols written to slot1_data
*
* 36.211 10.3 section 6.6.4
*
* @param[in] pbch PBCH complex symbols to place in slot1_data
* @param[out] slot1_data Complex symbol buffer for slot1
* @param[in] cell Cell configuration
*/
int srslte_pbch_put(cf_t *pbch, cf_t *slot1_data, srslte_cell_t cell) {
return srslte_pbch_cp(pbch, slot1_data, cell, true);
@ -122,6 +126,10 @@ int srslte_pbch_put(cf_t *pbch, cf_t *slot1_data, srslte_cell_t cell) {
* Returns the number of symbols written to pbch
*
* 36.211 10.3 section 6.6.4
*
* @param[in] slot1_data Complex symbols for slot1
* @param[out] pbch Extracted complex PBCH symbols
* @param[in] cell Cell configuration
*/
int srslte_pbch_get(cf_t *slot1_data, cf_t *pbch, srslte_cell_t cell) {
return srslte_pbch_cp(slot1_data, pbch, cell, false);
@ -244,8 +252,12 @@ void srslte_pbch_free(srslte_pbch_t *q) {
}
/** Unpacks MIB from PBCH message.
* msg buffer must be 24 byte length at least
/**
* Unpacks MIB from PBCH message.
*
* @param[in] msg PBCH in an unpacked bit array of size 24
* @param[out] sfn System frame number
* @param[out] cell MIB information about PHICH and system bandwidth will be saved here
*/
void srslte_pbch_mib_unpack(uint8_t *msg, srslte_cell_t *cell, uint32_t *sfn) {
int phich_res;
@ -289,8 +301,12 @@ void srslte_pbch_mib_unpack(uint8_t *msg, srslte_cell_t *cell, uint32_t *sfn) {
}
}
/** Unpacks MIB from PBCH message.
* msg buffer must be 24 byte length at least
/**
* Packs MIB to PBCH message.
*
* @param[out] payload Output unpacked bit array of size 24
* @param[in] sfn System frame number
* @param[in] cell Cell configuration to be encoded in MIB
*/
void srslte_pbch_mib_pack(srslte_cell_t *cell, uint32_t sfn, uint8_t *payload) {
int bw, phich_res = 0;

77
srslte/lib/phch/pdcch.c
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@ -56,7 +56,13 @@ void srslte_pdcch_set_cfi(srslte_pdcch_t *q, uint32_t cfi) {
set_cfi(q, cfi);
}
/** Initializes the PDCCH transmitter and receiver */
/**
* Initializes the PDCCH transmitter and receiver structure
*
* @param[out] q PDCCH structure to initialize
* @param[in] regs PDCCH structure stores a reference to regs
* @param[in] cell PDCCH structure stores a copy of cell
*/
int srslte_pdcch_init(srslte_pdcch_t *q, srslte_regs_t *regs, srslte_cell_t cell) {
int ret = SRSLTE_ERROR_INVALID_INPUTS;
uint32_t i;
@ -172,6 +178,16 @@ void srslte_pdcch_free(srslte_pdcch_t *q) {
}
/**
* Calculate DCI locations in UE-specific space and set CFI
*
* @param[out] c Buffer of length max_candidates for storing calculated DCI locations
* @param[in] max_candidates Size of buffer c
* @param[in] cfi Control Format Indicator. Affects length of PDCCH, thus there's more locations
* @param[in] nsubframe Subframe to calculate DCI locations for
* @param[in] rnti Destination RNTI
* @return Number of DCI locations stored in c
*/
uint32_t srslte_pdcch_ue_locations(srslte_pdcch_t *q, srslte_dci_location_t *c, uint32_t max_candidates,
uint32_t nsubframe, uint32_t cfi, uint16_t rnti)
{
@ -229,10 +245,19 @@ uint32_t srslte_pdcch_ue_locations_ncce(uint32_t nof_cce, srslte_dci_location_t
/**
* Calculate DCI locations for common search space and set PDCCH CFI
*
* 36.213 9.1.1
* Computes up to max_candidates candidates in the common search space
* First sets Control Format Indicator.
* Then computes up to max_candidates candidates in the common search space
* for DCI messages and saves them in the structure pointed by c.
* Returns the number of candidates saved in the array c.
*
* @param[inout] q PDCCH information. q->cfi is set to cfi.
* @param[out] c Buffer of length max_candidates for storing calculated DCI locations
* @param[in] max_candidates Size of buffer c
* @param[in] cfi Control Format Indicator. Affects length of PDCCH, thus there's more locations. Also it is copied to q->cfi
* @return Number of DCI locations stored in c
*/
uint32_t srslte_pdcch_common_locations(srslte_pdcch_t *q, srslte_dci_location_t *c, uint32_t max_candidates,
uint32_t cfi)
@ -241,6 +266,14 @@ uint32_t srslte_pdcch_common_locations(srslte_pdcch_t *q, srslte_dci_location_t
return srslte_pdcch_common_locations_ncce(q->nof_cce, c, max_candidates);
}
/**
* Calculate DCI locations for common search space
*
* @param[out] c Buffer of length max_candidates for storing calculated DCI locations
* @param[in] max_candidates Size of buffer c
* @param[in] cfi Control Format Indicator. Affects length of PDCCH, thus there's more locations
* @return Number of DCI locations stored in c
*/
uint32_t srslte_pdcch_common_locations_ncce(uint32_t nof_cce, srslte_dci_location_t *c, uint32_t max_candidates)
{
uint32_t i, l, L, k;
@ -447,7 +480,12 @@ int srslte_pdcch_extract_llr(srslte_pdcch_t *q, cf_t *sf_symbols, cf_t *ce[SRSLT
}
/**
* Unpacks RNTI into a bit array and XORs with bit array in crc
*
* @param[in] crc Location to XOR unpacked RNTI to
* @param[in] rnti RNTI to unpack and XOR
*/
static void crc_set_mask_rnti(uint8_t *crc, uint16_t rnti) {
uint32_t i;
uint8_t mask[16];
@ -461,6 +499,14 @@ static void crc_set_mask_rnti(uint8_t *crc, uint16_t rnti) {
}
}
/**
* Appends CRC to a packed DCI message. Applies convolution encoding. Does not do rate matching.
*
* @param[in] data Unpacked bit array. MSB first.
* @param[in] nof_bits Length of data array
* @param[out] coded_data Output unpacked bit array. Size (nof_bits+16)*3
* @param[in] rnti Destination RNTI
*/
void srslte_pdcch_dci_encode_conv(srslte_pdcch_t *q, uint8_t *data, uint32_t nof_bits, uint8_t *coded_data, uint16_t rnti) {
srslte_convcoder_t encoder;
int poly[3] = { 0x6D, 0x4F, 0x57 };
@ -475,8 +521,21 @@ void srslte_pdcch_dci_encode_conv(srslte_pdcch_t *q, uint8_t *data, uint32_t nof
srslte_convcoder_encode(&encoder, data, coded_data, nof_bits + 16);
}
/** 36.212 5.3.3.2 to 5.3.3.4
* TODO: UE transmit antenna selection CRC mask
/**
* Appends CRC to a packed DCI message. Applies convolution encoding. Does rate matching.
*
* 36.212 5.3.3.2 to 5.3.3.4
* @TODO: UE transmit antenna selection CRC mask
*
* @param[in] data Unpacked bit array. MSB first.
* @param[in] nof_bits Length of data array
* @param[in] E Rate match to this size buffer
* @param[out] e Output unpacked bit array. Size E
* @param[in] rnti Destination RNTI
* @return Error code
*/
/**
*
*/
int srslte_pdcch_dci_encode(srslte_pdcch_t *q, uint8_t *data, uint8_t *e, uint32_t nof_bits, uint32_t E,
uint16_t rnti)
@ -512,6 +571,14 @@ int srslte_pdcch_dci_encode(srslte_pdcch_t *q, uint8_t *data, uint8_t *e, uint32
* If the same location is provided in multiple messages, the encoded bits will be overwritten.
*
* @TODO: Use a bitmask and CFI to ensure message locations are valid and old messages are not overwritten.
*
* @param[in] q PDCCH parameters
* @param[in] msg Input DCI message buffer
* @param[in] location
* @param[in] rnti Destination RNTI
* @param[out] sf_symbols Pointers to all symbols in a subframe for all antenna ports
* @param[in] nsubframe Current subframe index. Affects scrambling and UE-specific DCI message locations
* @param[in] cfi Control Format Indicator
*/
int srslte_pdcch_encode(srslte_pdcch_t *q, srslte_dci_msg_t *msg, srslte_dci_location_t location, uint16_t rnti,
cf_t *sf_symbols[SRSLTE_MAX_PORTS], uint32_t nsubframe, uint32_t cfi)

15
srslte/lib/phch/ra.c
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@ -268,7 +268,11 @@ uint32_t srslte_ra_dl_grant_nof_re(srslte_ra_dl_grant_t *grant, srslte_cell_t ce
return nof_re;
}
/** Compute PRB allocation for Downlink as defined in 7.1.6 of 36.213 */
/** Compute PRB allocation for Downlink as defined in 7.1.6 of 36.213
* Decode dci->type?_alloc to grant
* This function only reads dci->type?_alloc and dci->alloc_type fields.
* This function only writes grant->prb_idx and grant->nof_prb.
*/
static int dl_dci_to_grant_prb_allocation(srslte_ra_dl_dci_t *dci, srslte_ra_dl_grant_t *grant, uint32_t nof_prb) {
int i, j;
uint32_t bitmask;
@ -381,7 +385,7 @@ static int dl_dci_to_grant_prb_allocation(srslte_ra_dl_dci_t *dci, srslte_ra_dl_
return SRSLTE_SUCCESS;
}
static int dl_fill_ra_mcs(srslte_ra_mcs_t *mcs, uint32_t nprb) {
int dl_fill_ra_mcs(srslte_ra_mcs_t *mcs, uint32_t nprb) {
uint32_t i_tbs = 0;
int tbs = -1;
if (mcs->idx < 10) {
@ -415,7 +419,12 @@ static int dl_fill_ra_mcs(srslte_ra_mcs_t *mcs, uint32_t nprb) {
return tbs;
}
/* Modulation order and transport block size determination 7.1.7 in 36.213 */
/* Modulation order and transport block size determination 7.1.7 in 36.213
* This looks at DCI type, type of RNTI and reads fields dci->type?_alloc, dci->mcs_idx,
* dci->dci_is_1a and dci->dci_is_1c
* Reads global variable last_dl_tbs if mcs>=29
* Writes global variable last_dl_tbs if mcs<29
* */
static int dl_dci_to_grant_mcs(srslte_ra_dl_dci_t *dci, srslte_ra_dl_grant_t *grant, bool crc_is_crnti) {
uint32_t n_prb=0;
int tbs = -1;

24
srslte/lib/phch/sch.c
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@ -314,8 +314,18 @@ static int encode_tb(srslte_sch_t *q,
/* Decode a transport block according to 36.212 5.3.2
/**
* Decode a transport block according to 36.212 5.3.2
*
* @param[in] q
* @param[inout] softbuffer Initialized softbuffer
* @param[in] cb_segm Code block segmentation parameters
* @param[in] e_bits Input transport block
* @param[in] Qm Modulation type
* @param[in] rv Redundancy Version. Indicates which part of FEC bits is in input buffer
* @param[out] softbuffer Initialized output softbuffer
* @param[out] data Decoded transport block
* @return negative if error in parameters or CRC error in decoding
*/
static int decode_tb(srslte_sch_t *q,
srslte_softbuffer_rx_t *softbuffer, srslte_cbsegm_t *cb_segm,
@ -351,7 +361,7 @@ static int decode_tb(srslte_sch_t *q,
if (cb_segm->C > softbuffer->max_cb) {
fprintf(stderr, "Error number of CB (%d) exceeds soft buffer size (%d CBs)\n", cb_segm->C, softbuffer->max_cb);
return -1;
return SRSLTE_ERROR;
}
if (cb_segm->C>0) {
@ -489,6 +499,16 @@ int srslte_dlsch_decode(srslte_sch_t *q, srslte_pdsch_cfg_t *cfg, srslte_softbuf
e_bits, data);
}
/**
* Encode transport block. Segments into code blocks, adds channel coding, and does rate matching.
*
* @param[in] q Initialized
* @param[in] cfg Encoding parameters
* @param[inout] softbuffer Initialized softbuffer
* @param[in] data Byte array of data. Size is implicit in cfg->cb_segm
* @param e_bits
* @return Error code
*/
int srslte_dlsch_encode(srslte_sch_t *q, srslte_pdsch_cfg_t *cfg, srslte_softbuffer_tx_t *softbuffer,
uint8_t *data, uint8_t *e_bits)
{

16
srslte/lib/utils/bit.c
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@ -209,6 +209,15 @@ bitarray_copy(const unsigned char *src_org, int src_offset, int src_len,
}
}
/**
* Copy bits from src to dst, with offsets and length in bits
*
* @param[out] dst Output array
* @param[in] src Input array
* @param dst_offset Output array write offset in bits
* @param src_offset Input array read offset in bits
* @param nof_bits Number of bits to copy
*/
void srslte_bit_copy(uint8_t *dst, uint32_t dst_offset, uint8_t *src, uint32_t src_offset, uint32_t nof_bits)
{
static const uint8_t mask_dst[] =
@ -247,6 +256,13 @@ void srslte_bit_unpack_l(uint64_t value, uint8_t **bits, int nof_bits)
*bits += nof_bits;
}
/**
* Unpacks nof_bits from LSBs of value in MSB order to *bits. Advances pointer past unpacked bits.
*
* @param[in] value nof_bits lowest order bits will be unpacked in MSB order
* @param[in] nof_bits Number of bits to unpack
* @param[out] bits Points to buffer pointer. The buffer pointer will be advanced by nof_bits
*/
void srslte_bit_unpack(uint32_t value, uint8_t **bits, int nof_bits)
{
int i;

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