CDCcomm.cpp

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/*
 * CDCcomm.cpp
 *
 *  Created on: 17.11.2021
 *      Author: Yannick
 *
 *      Contains functions to interface a usb CDC port
 */
 
#include "CDCcomm.h"
#include "tusb.h"
 
// Flag to trigger another send call
bool CDCcomm::usb_busy_retry = false;
std::string CDCcomm::remainingStrs[CFG_TUD_CDC] = {""};
std::string CDCcomm::tString;
cpp_freertos::BinarySemaphore CDCcomm::cdcSems[CFG_TUD_CDC] = {cpp_freertos::BinarySemaphore(true)};
 
CDCcomm::CDCcomm() {
 
}
 
CDCcomm::~CDCcomm() {
 
}
 
 
void CDCcomm::cdcFinished(uint8_t itf){
    cdcSems[itf].Give();
    if(CDCcomm::usb_busy_retry && CDCcomm::remainingStrs[itf].length() > 0){
        cdcSend(&CDCcomm::remainingStrs[itf], itf); // Retry with remaining string
    }
    if(CDCcomm::remainingStrs[itf].capacity() > 512){
        CDCcomm::remainingStrs[itf].shrink_to_fit(); // Prevent permanent increase of size if a long command was buffered
    }
}
 
uint32_t CDCcomm::remainingData(uint8_t itf){
    return CDCcomm::remainingStrs[itf].size();
}
 
void CDCcomm::clearRemainingBuffer(uint8_t itf){
    CDCcomm::remainingStrs[itf].clear();
}
 
bool CDCcomm::connected(uint8_t itf){
    return tud_cdc_n_connected(itf);
}
 
uint16_t CDCcomm::cdcSend(std::string* reply,uint8_t itf){
    if(!tud_ready() || reply->empty()){ // TODO check if connected when gui sets DTR
        return 0;
    }
    cdcSems[itf].Take();
    uint32_t bufferRemaining = tud_cdc_n_write_available(itf);
    uint32_t cdc_sent = tud_cdc_n_write(itf,reply->c_str(), std::min<uint16_t>(reply->length(),bufferRemaining));
    if(!usb_busy_retry) // We did not retransmit so flush now. otherwise TUD will flush if we were in the callback before
        tud_cdc_n_write_flush(itf);
 
    // If we can't write the whole reply copy remainder to send later
    if(cdc_sent < reply->length()){
        remainingStrs[itf] = reply->substr(cdc_sent);
        usb_busy_retry = true;
        remainingStrs[itf].shrink_to_fit();
    }else{
        usb_busy_retry = false;
        remainingStrs[itf].clear();
    }
 
    return cdc_sent;
}