From 8a89804fda5f5de86cebb84df083ca8ae463134c Mon Sep 17 00:00:00 2001 From: Cort Buffington Date: Tue, 11 Aug 2026 08:55:22 -0500 Subject: [PATCH] Refactor FM_LINK_EXT_GAP_MS and improve comments Updated the FM_LINK_EXT_GAP_MS constant declaration and added comments for clarity. --- FM.cpp | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/FM.cpp b/FM.cpp index c8ac3a2..efe3e05 100644 --- a/FM.cpp +++ b/FM.cpp @@ -27,14 +27,8 @@ const uint16_t FM_TX_BLOCK_SIZE = 100U; const uint16_t FM_SERIAL_BLOCK_SIZE = 80U;//this is the number of sample pairs to send over serial. One sample pair is 3bytes. //three times this value shall never exceed 252 const uint16_t FM_SERIAL_BLOCK_SIZE_BYTES = FM_SERIAL_BLOCK_SIZE * 3U; - -// How long a link-mode external-audio underrun is tolerated before it is -// treated as a real end of transmission (see linkStateMachine()). A gap -// shorter than this is inaudible on its own; the PTT drop-and-rekey it -// would otherwise trigger is not. Tune here if needed -- no other code -// depends on this value. -const uint16_t FM_LINK_EXT_GAP_MS = 60U; - +const uint16_t FM_LINK_EXT_GAP_MS = 60U;// How long a link-mode external-audio underrun is tolerated before it is + // treated as a real end of transmission (see linkStateMachine()). const uint8_t FS_LISTENING = 0U; const uint8_t FS_KERCHUNK_RF = 1U; const uint8_t FS_RELAYING_RF = 2U; @@ -259,7 +253,6 @@ void CFM::linkSamples(bool cos, q15_t* samples, uint8_t length) uint8_t i = 0U; for (; i < length; i++) { - // ARMv7-M has hardware integer division q15_t currentRFSample = q15_t((q31_t(samples[i]) << 8) / m_rxLevel); if (m_noiseSquelch) @@ -267,8 +260,7 @@ void CFM::linkSamples(bool cos, q15_t* samples, uint8_t length) // Zero-initialized: getSample() leaves this untouched on underrun, and // with the ext-gap debounce below, m_extSignal can now stay true for a - // few samples past that point -- silence, not stack garbage, must be - // what gets played out to the modem in that window. + // few samples past that point q15_t currentExtSample = 0; bool inputExt = m_inputExtRB.getSample(currentExtSample);//always consume the external input data so it does not overflow inputExt = inputExt && m_extEnabled; @@ -1272,9 +1264,9 @@ void CFM::linkStateMachine(bool validRFSignal, bool validExtSignal) // the very first bad sample, with zero debounce -- that is what // actually keys the transmitter off (IO::process() drops PTT the // instant the downstream TX buffer runs dry, see IO.cpp). A gap well - // under FM_LINK_EXT_GAP_MS is inaudible on its own; the PTT - // drop-and-rekey it triggers is not. Give it a short grace period - // instead, mirroring the RELAYING_EXT/RELAYING_WAIT_EXT pattern the + // under FM_LINK_EXT_GAP_MS is less offensive than the PTT + // drop-and-rekey it triggers. Give it a short grace period + // mirroring the RELAYING_EXT/RELAYING_WAIT_EXT pattern the // non-link duplex/simplex paths already use for exactly this // situation (see relayingExtStateDuplex()/relayingExtWaitStateDuplex()). if (!m_extGapTimer.isRunning()) {