From 7b4101b9755081d574158434c79471a59b4b27a0 Mon Sep 17 00:00:00 2001
From: Tim Sawyer <tisawyer@gmail.com>
Date: Tue, 3 Mar 2026 17:08:40 -0800
Subject: [PATCH] Port V24 pre-#7 startup baseline onto master

---
 .gitignore                  |  3 +++
 src/host/Host.P25.cpp       |  7 ++++++-
 src/host/modem/Modem.cpp    |  9 +++++++--
 src/host/modem/ModemV24.cpp | 11 ++++-------
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/.gitignore b/.gitignore
index 247a1564..531f09d4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,6 +23,9 @@ _deps
 # Ignore thumbnails created by windows
 Thumbs.db
 
+# Ignore macOS Finder metadata files
+.DS_Store
+
 # Ignore files created by clang-check
 *.plist
 
diff --git a/src/host/Host.P25.cpp b/src/host/Host.P25.cpp
index 1db6a6ba..9c5f3e71 100644
--- a/src/host/Host.P25.cpp
+++ b/src/host/Host.P25.cpp
@@ -255,6 +255,11 @@ void* Host::threadP25Writer(void* arg)
 
                         if (nextLen > 0U) {
                             bool ret = host->m_modem->hasP25Space(nextLen);
+                            // V.24 modem status space can lag at call start; do not block
+                            // initial Net->RF voice frames on stale p25Space accounting.
+                            if (!ret && host->m_modem->isV24Connected()) {
+                                ret = true;
+                            }
                             if (ret) {
                                 bool imm = false;
                                 uint32_t len = host->m_p25->getFrame(data, &imm);
@@ -267,7 +272,7 @@ void* Host::threadP25Writer(void* arg)
 
                                     // if the state is P25; write P25 frame data
                                     if (host->m_state == STATE_P25) {
-                                        host->m_modem->writeP25Frame(data, len);
+                                        host->m_modem->writeP25Frame(data, len, imm);
 
                                         afterWriteCallback();
 
diff --git a/src/host/modem/Modem.cpp b/src/host/modem/Modem.cpp
index 18a95e3f..3ff080d4 100644
--- a/src/host/modem/Modem.cpp
+++ b/src/host/modem/Modem.cpp
@@ -1517,7 +1517,10 @@ bool Modem::writeP25Frame(const uint8_t* data, uint32_t length, bool imm)
         uint32_t len = length + 2U;
 
         // write or buffer P25 data to air interface
-        if (m_p25Space >= length) {
+        //
+        // For V.24/DFSI, the modem status space value may lag call startup; do
+        // not block initial Net->RF frames solely on stale p25Space.
+        if (m_p25Space >= length || isV24Connected()) {
             if (m_debug)
                 LogDebugEx(LOG_MODEM, "Modem::writeP25Frame()", "immediate write (len %u)", length);
             if (m_trace)
@@ -1529,7 +1532,9 @@ bool Modem::writeP25Frame(const uint8_t* data, uint32_t length, bool imm)
                 return false;
             }
 
-            m_p25Space -= length;
+            if (m_p25Space >= length) {
+                m_p25Space -= length;
+            }
         }
         else {
             return false;
diff --git a/src/host/modem/ModemV24.cpp b/src/host/modem/ModemV24.cpp
index eb2b9e2a..695464ef 100644
--- a/src/host/modem/ModemV24.cpp
+++ b/src/host/modem/ModemV24.cpp
@@ -394,10 +394,11 @@ void ModemV24::clock(uint32_t ms)
     int len = 0;
 
     // write anything waiting to the serial port
-    if (!m_txImmP25Queue.isEmpty())
+    //
+    // Keep normal queue first for startup consistency with older behavior.
+    len = writeSerial(&m_txP25Queue);
+    if (len == 0 && !m_txImmP25Queue.isEmpty())
         len = writeSerial(&m_txImmP25Queue);
-    else
-        len = writeSerial(&m_txP25Queue);
     if (m_debug && len > 0) {
         LogDebug(LOG_MODEM, "Wrote %u-byte message to the serial V24 device", len);
     } else if (len < 0) {
@@ -496,10 +497,6 @@ int ModemV24::writeSerial(RingBuffer<uint8_t>* queue)
         return 0U;
     }
 
-    // check available modem space
-    if (m_p25Space < len)
-        return 0U;
-
     std::lock_guard<std::mutex> lock(m_txP25QueueLock);
 
     // get current timestamp