From 57a42e3ce9dab67b080ff3b9a4a5f9e79b1c12d6 Mon Sep 17 00:00:00 2001
From: Antiklesys <syselkitna@gmail.com>
Date: Sat, 5 Sep 2026 22:31:52 +0800
Subject: [PATCH] Stability fix for sc-bigbuf traces

---
 armsrc/BigBuf.c   | 10 +++++++++-
 armsrc/BigBuf.h   |  1 +
 armsrc/appmain.c  |  4 ++++
 armsrc/sam_sc.c   |  9 +++++++++
 armsrc/sam_sc.h   |  1 +
 include/pm3_cmd.h |  1 +
 6 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/armsrc/BigBuf.c b/armsrc/BigBuf.c
index 5e84dce1b..cfd495c5d 100644
--- a/armsrc/BigBuf.c
+++ b/armsrc/BigBuf.c
@@ -75,6 +75,7 @@ static dmabuf8_t s_dma_8 = {
 // trace related variables
 static uint32_t s_trace_len = 0;
 static bool s_tracing = true;
+static bool s_tracing_blocked = false;
 
 static uint32_t s_trace_origin = 0;
 static bool s_trace_origin_valid = false;
@@ -231,7 +232,14 @@ void set_tracelen(uint32_t value) {
 }
 
 void set_tracing(bool enable) {
-    s_tracing = enable;
+    s_tracing = enable && !s_tracing_blocked;
+}
+
+bool set_tracing_blocked(bool blocked) {
+    bool previous = s_tracing_blocked;
+    s_tracing_blocked = blocked;
+    if (blocked) s_tracing = false;
+    return previous;
 }
 
 bool get_tracing(void) {
diff --git a/armsrc/BigBuf.h b/armsrc/BigBuf.h
index 640422c57..fa763cf22 100644
--- a/armsrc/BigBuf.h
+++ b/armsrc/BigBuf.h
@@ -55,6 +55,7 @@ void BigBuf_print_status(void);
 uint32_t BigBuf_get_traceLen(void);
 void clear_trace(void);
 void set_tracing(bool enable);
+bool set_tracing_blocked(bool blocked); // Returns the previous block state.
 void set_tracelen(uint32_t value);
 bool get_tracing(void);
 
diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index ea4896e76..5e4551c1d 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -2936,6 +2936,10 @@ static void PacketReceived(PacketCommandNG *packet) {
             sam_sc_handler(packet);
             break;
         }
+        case CMD_HF_SAM_SC_NO_TRACE: {
+            sam_sc_handler_no_trace(packet);
+            break;
+        }
 
 #endif
 
diff --git a/armsrc/sam_sc.c b/armsrc/sam_sc.c
index c1f6dd93a..8b196174e 100644
--- a/armsrc/sam_sc.c
+++ b/armsrc/sam_sc.c
@@ -453,6 +453,15 @@ static int sam_sc_card_api_loop(uint8_t *response, uint16_t *response_len,
     return res;
 }
 
+void sam_sc_handler_no_trace(const PacketCommandNG *c) {
+    const bool tracing = get_tracing();
+    const bool blocked = set_tracing_blocked(true);
+    clear_trace();
+    sam_sc_handler(c);
+    set_tracing_blocked(blocked);
+    set_tracing(tracing);
+}
+
 void sam_sc_handler(const PacketCommandNG *c) {
 
     if (c == NULL || c->length < SAM_SC_HEADER_LEN) {
diff --git a/armsrc/sam_sc.h b/armsrc/sam_sc.h
index da45c89e3..013247352 100644
--- a/armsrc/sam_sc.h
+++ b/armsrc/sam_sc.h
@@ -93,6 +93,7 @@
 #define SAM_SC_ADDR_SNMP_LOADER 0xff
 
 void sam_sc_handler(const PacketCommandNG *c);
+void sam_sc_handler_no_trace(const PacketCommandNG *c);
 
 // Forces the next sam_sc_handler() call to perform an I2C reset before sending
 // its payload. Intended to be called by other firmware paths that may have
diff --git a/include/pm3_cmd.h b/include/pm3_cmd.h
index 452a2cbc7..bfcc87e24 100644
--- a/include/pm3_cmd.h
+++ b/include/pm3_cmd.h
@@ -1205,6 +1205,7 @@ typedef struct {
 // session state must persist across calls (no I2C reset, no GetVersion ping,
 // no iso15 NFC-relay loop) and the routing scFlag byte must be host-supplied.
 #define CMD_HF_SAM_SC 0x0904
+#define CMD_HF_SAM_SC_NO_TRACE 0x0905 // Same payload and reply command as CMD_HF_SAM_SC.
 
 #define CMD_UNKNOWN 0xFFFF