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/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.1 (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.openairinterface.org/?page_id=698
*
* 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.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
/* file: lte_segmentation.c
purpose: Procedures for transport block segmentation for LTE (turbo-coded transport channels)
author: raymond.knopp@eurecom.fr
date: 21.10.2009
*/
#include "PHY/defs.h"
#include "SCHED/extern.h"
//#define DEBUG_SEGMENTATION
int lte_segmentation(unsigned char *input_buffer,
unsigned char **output_buffers,
unsigned int B,
unsigned int *C,
unsigned int *Cplus,
unsigned int *Cminus,
unsigned int *Kplus,
unsigned int *Kminus,
unsigned int *F)
{
unsigned int L,Bprime,Bprime_by_C,r,Kr,k,s,crc;
if (B<=6144) {
L=0;
*C=1;
Bprime=B;
} else {
L=24;
*C = B/(6144-L);
if ((6144-L)*(*C) < B)
*C=*C+1;
Bprime = B+((*C)*L);
#ifdef DEBUG_SEGMENTATION
printf("Bprime %d\n",Bprime);
#endif
}
if ((*C)>MAX_NUM_DLSCH_SEGMENTS) {
LOG_E(PHY,"lte_segmentation.c: too many segments %d, B %d, L %d, Bprime %d\n",*C,B,L,Bprime);
return(-1);
}
// Find K+
Bprime_by_C = Bprime/(*C);
#ifdef DEBUG_SEGMENTATION
printf("Bprime_by_C %d\n",Bprime_by_C);
#endif
// Bprime = Bprime_by_C>>3;
if (Bprime_by_C <= 40) {
*Kplus = 40;
*Kminus = 0;
} else if (Bprime_by_C<=512) { // increase by 1 byte til here
*Kplus = (Bprime_by_C>>3)<<3;
*Kminus = Bprime_by_C-8;
} else if (Bprime_by_C <=1024) { // increase by 2 bytes til here
*Kplus = (Bprime_by_C>>4)<<4;
if (*Kplus < Bprime_by_C)
*Kplus = *Kplus + 16;
*Kminus = (*Kplus - 16);
} else if (Bprime_by_C <= 2048) { // increase by 4 bytes til here
*Kplus = (Bprime_by_C>>5)<<5;
if (*Kplus < Bprime_by_C)
*Kplus = *Kplus + 32;
*Kminus = (*Kplus - 32);
} else if (Bprime_by_C <=6144 ) { // increase by 8 bytes til here
*Kplus = (Bprime_by_C>>6)<<6;
#ifdef DEBUG_SEGMENTATION
printf("Bprime_by_C_by_C %d , Kplus %d\n",Bprime_by_C,*Kplus);
#endif
if (*Kplus < Bprime_by_C)
*Kplus = *Kplus + 64;
#ifdef DEBUG_SEGMENTATION
printf("Bprime_by_C_by_C %d , Kplus2 %d\n",Bprime_by_C,*Kplus);
#endif
*Kminus = (*Kplus - 64);
} else {
printf("lte_segmentation.c: Illegal codeword size !!!\n");
return(-1);
}
if (*C == 1) {
*Cplus = *C;
*Kminus = 0;
*Cminus = 0;
} else {
// printf("More than one segment (%d), exiting \n",*C);
// exit(-1);
*Cminus = ((*C)*(*Kplus) - (Bprime))/((*Kplus) - (*Kminus));
*Cplus = (*C) - (*Cminus);
}
AssertFatal(Bprime <= (*Cplus)*(*Kplus) + (*Cminus)*(*Kminus),
"Bprime %d < (*Cplus %d)*(*Kplus %d) + (*Cminus %d)*(*Kminus %d)\n",
Bprime,*Cplus,*Kplus,*Cminus,*Kminus);
*F = ((*Cplus)*(*Kplus) + (*Cminus)*(*Kminus) - (Bprime));
#ifdef DEBUG_SEGMENTATION
printf("C %d, Cplus %d, Cminus %d, Kplus %d, Kminus %d, Bprime_bytes %d, Bprime %d, F %d\n",*C,*Cplus,*Cminus,*Kplus,*Kminus,Bprime>>3,Bprime,*F);
#endif
if ((input_buffer) && (output_buffers)) {
for (k=0; k<*F>>3; k++) {
output_buffers[0][k] = 0;
}
s=0;
for (r=0; r<*C; r++) {
if (r<*Cminus)
Kr = *Kminus;
else
Kr = *Kplus;
while (k<((Kr - L)>>3)) {
output_buffers[r][k] = input_buffer[s];
// printf("encoding segment %d : byte %d (%d) => %d\n",r,k,Kr>>3,input_buffer[s]);
k++;
s++;
}
if (*C > 1) { // add CRC
crc = crc24b(output_buffers[r],Kr-24)>>8;
output_buffers[r][(Kr-24)>>3] = ((uint8_t*)&crc)[2];
output_buffers[r][1+((Kr-24)>>3)] = ((uint8_t*)&crc)[1];
output_buffers[r][2+((Kr-24)>>3)] = ((uint8_t*)&crc)[0];
#ifdef DEBUG_SEGMENTATION
printf("Segment %d : CRC %x\n",r,crc);
#endif
}
k=0;
}
}
return(0);
}
#ifdef MAIN
main()
{
unsigned int Kplus,Kminus,C,Cplus,Cminus,F,Bbytes;
for (Bbytes=5; Bbytes<2*768; Bbytes++) {
lte_segmentation(0,0,Bbytes<<3,&C,&Cplus,&Cminus,&Kplus,&Kminus,&F);
printf("Bbytes %d : C %d, Cplus %d, Cminus %d, Kplus %d, Kminus %d, F %d\n",
Bbytes, C, Cplus, Cminus, Kplus, Kminus, F);
}
}
#endif