| /* |
| * Radio device interface with sample rate conversion |
| * Written by Thomas Tsou <tom@tsou.cc> |
| * |
| * Copyright 2011, 2012, 2013 Free Software Foundation, Inc. |
| * |
| * This program is free software: you can redistribute it and/or modify |
| * it under the terms of the GNU Affero General Public License as published by |
| * the Free Software Foundation, either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Affero General Public License for more details. |
| * |
| * You should have received a copy of the GNU Affero General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| * See the COPYING file in the main directory for details. |
| */ |
| |
| #include <radioInterface.h> |
| #include <Logger.h> |
| |
| #include "Resampler.h" |
| |
| extern "C" { |
| #include "convert.h" |
| } |
| |
| /* Resampling parameters for 100 MHz clocking */ |
| #define RESAMP_INRATE 52 |
| #define RESAMP_OUTRATE 75 |
| |
| /* |
| * Resampling filter bandwidth scaling factor |
| * This narrows the filter cutoff relative to the output bandwidth |
| * of the polyphase resampler. At 4 samples-per-symbol using the |
| * 2 pulse Laurent GMSK approximation gives us below 0.5 degrees |
| * RMS phase error at the resampler output. |
| */ |
| #define RESAMP_TX4_FILTER 0.45 |
| |
| #define INCHUNK (RESAMP_INRATE * 4) |
| #define OUTCHUNK (RESAMP_OUTRATE * 4) |
| |
| static Resampler *upsampler = NULL; |
| static Resampler *dnsampler = NULL; |
| short *convertRecvBuffer = NULL; |
| short *convertSendBuffer = NULL; |
| |
| RadioInterfaceResamp::RadioInterfaceResamp(RadioDevice *wRadio, |
| int wReceiveOffset, |
| int wSPS, |
| GSM::Time wStartTime) |
| : RadioInterface(wRadio, wReceiveOffset, wSPS, wStartTime), |
| innerSendBuffer(NULL), outerSendBuffer(NULL), |
| innerRecvBuffer(NULL), outerRecvBuffer(NULL) |
| { |
| } |
| |
| RadioInterfaceResamp::~RadioInterfaceResamp() |
| { |
| close(); |
| } |
| |
| void RadioInterfaceResamp::close() |
| { |
| RadioInterface::close(); |
| |
| delete innerSendBuffer; |
| delete outerSendBuffer; |
| delete innerRecvBuffer; |
| delete outerRecvBuffer; |
| |
| delete upsampler; |
| delete dnsampler; |
| |
| innerSendBuffer = NULL; |
| outerSendBuffer = NULL; |
| innerRecvBuffer = NULL; |
| outerRecvBuffer = NULL; |
| |
| upsampler = NULL; |
| dnsampler = NULL; |
| } |
| |
| /* Initialize I/O specific objects */ |
| bool RadioInterfaceResamp::init() |
| { |
| float cutoff = 1.0f; |
| |
| close(); |
| |
| if (mSPSTx == 4) |
| cutoff = RESAMP_TX4_FILTER; |
| |
| dnsampler = new Resampler(RESAMP_INRATE, RESAMP_OUTRATE); |
| if (!dnsampler->init()) { |
| LOG(ALERT) << "Rx resampler failed to initialize"; |
| return false; |
| } |
| |
| upsampler = new Resampler(RESAMP_OUTRATE, RESAMP_INRATE); |
| if (!upsampler->init(cutoff)) { |
| LOG(ALERT) << "Tx resampler failed to initialize"; |
| return false; |
| } |
| |
| /* |
| * Allocate high and low rate buffers. The high rate receive |
| * buffer and low rate transmit vectors feed into the resampler |
| * and requires headroom equivalent to the filter length. Low |
| * rate buffers are allocated in the main radio interface code. |
| */ |
| innerSendBuffer = new signalVector(INCHUNK * 20, upsampler->len()); |
| outerSendBuffer = new signalVector(OUTCHUNK * 20); |
| |
| outerRecvBuffer = new signalVector(OUTCHUNK * 2, dnsampler->len()); |
| innerRecvBuffer = new signalVector(INCHUNK * 20); |
| |
| convertSendBuffer = new short[OUTCHUNK * 2 * 20]; |
| convertRecvBuffer = new short[OUTCHUNK * 2 * 2]; |
| |
| sendBuffer = innerSendBuffer; |
| recvBuffer = innerRecvBuffer; |
| |
| return true; |
| } |
| |
| /* Receive a timestamped chunk from the device */ |
| void RadioInterfaceResamp::pullBuffer() |
| { |
| bool local_underrun; |
| int rc, num_recv; |
| int inner_len = INCHUNK; |
| int outer_len = OUTCHUNK; |
| |
| /* Outer buffer access size is fixed */ |
| num_recv = mRadio->readSamples(convertRecvBuffer, |
| outer_len, |
| &overrun, |
| readTimestamp, |
| &local_underrun); |
| if (num_recv != outer_len) { |
| LOG(ALERT) << "Receive error " << num_recv; |
| return; |
| } |
| |
| convert_short_float((float *) outerRecvBuffer->begin(), |
| convertRecvBuffer, 2 * outer_len); |
| |
| underrun |= local_underrun; |
| readTimestamp += (TIMESTAMP) num_recv; |
| |
| /* Write to the end of the inner receive buffer */ |
| rc = dnsampler->rotate((float *) outerRecvBuffer->begin(), outer_len, |
| (float *) (innerRecvBuffer->begin() + recvCursor), |
| inner_len); |
| if (rc < 0) { |
| LOG(ALERT) << "Sample rate upsampling error"; |
| } |
| |
| recvCursor += inner_len; |
| } |
| |
| /* Send a timestamped chunk to the device */ |
| void RadioInterfaceResamp::pushBuffer() |
| { |
| int rc, chunks, num_sent; |
| int inner_len, outer_len; |
| |
| if (sendCursor < INCHUNK) |
| return; |
| |
| chunks = sendCursor / INCHUNK; |
| if (chunks > 8) |
| chunks = 8; |
| |
| inner_len = chunks * INCHUNK; |
| outer_len = chunks * OUTCHUNK; |
| |
| /* Always send from the beginning of the buffer */ |
| rc = upsampler->rotate((float *) innerSendBuffer->begin(), inner_len, |
| (float *) outerSendBuffer->begin(), outer_len); |
| if (rc < 0) { |
| LOG(ALERT) << "Sample rate downsampling error"; |
| } |
| |
| convert_float_short(convertSendBuffer, |
| (float *) outerSendBuffer->begin(), |
| powerScaling, 2 * outer_len); |
| |
| num_sent = mRadio->writeSamples(convertSendBuffer, |
| outer_len, |
| &underrun, |
| writeTimestamp); |
| if (num_sent != outer_len) { |
| LOG(ALERT) << "Transmit error " << num_sent; |
| } |
| |
| /* Shift remaining samples to beginning of buffer */ |
| memmove(innerSendBuffer->begin(), |
| innerSendBuffer->begin() + inner_len, |
| (sendCursor - inner_len) * 2 * sizeof(float)); |
| |
| writeTimestamp += outer_len; |
| sendCursor -= inner_len; |
| assert(sendCursor >= 0); |
| } |