From 7904d962aaff9c40e3253858bfb0f59b66ff804a Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Sat, 5 Sep 2020 12:50:30 +0200
Subject: [PATCH] timeout in waiting loops 4x50

---
 armsrc/em4x50.c | 42 +++++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 15 deletions(-)

diff --git a/armsrc/em4x50.c b/armsrc/em4x50.c
index bcc646fcc..45ffc8bbd 100644
--- a/armsrc/em4x50.c
+++ b/armsrc/em4x50.c
@@ -313,22 +313,36 @@ static int get_next_bit(void) {
 
 static uint32_t get_pulse_length(void) {
 
+    int32_t timeout = (T0 * 3 * EM4X50_T_TAG_FULL_PERIOD);
+
     // iterates pulse length (low -> high -> low)
 
-    uint8_t sample = 0;
+    volatile uint8_t sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
 
-    sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
-
-    while (sample > gLow)
+    while (sample > gLow || (timeout--)) {
         sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+    }
+    
+    if (timeout == 0)
+        return 0;
 
     AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
+    timeout = (T0 * 3 * EM4X50_T_TAG_FULL_PERIOD);
 
-    while (sample < gHigh)
+    while (sample < gHigh || (timeout--)) {
         sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+    }
 
-    while (sample > gLow)
+    if (timeout == 0)
+        return 0;
+
+    timeout = (T0 * 3 * EM4X50_T_TAG_FULL_PERIOD);
+    while (sample > gLow || (timeout--)) {
         sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
+    }
+
+    if (timeout == 0)
+        return 0;
 
     return (uint32_t)AT91C_BASE_TC1->TC_CV;
 }
@@ -413,13 +427,13 @@ static void em4x50_send_word(const uint8_t bytes[4]) {
     em4x50_send_bit(0);
 }
 
-static bool find_single_listen_window(int16_t timeout) {
+static bool find_single_listen_window(void) {
 
     // find single listen window
 
     int cnt_pulses = 0;
 
-    while (cnt_pulses < EM4X50_T_WAITING_FOR_SNGLLIW && timeout--) {
+    while (cnt_pulses < EM4X50_T_WAITING_FOR_SNGLLIW) {
 
         // identification of listen window is done via evaluation of
         // pulse lengths
@@ -432,16 +446,14 @@ static bool find_single_listen_window(int16_t timeout) {
 
             }
         } else {
-
             cnt_pulses++;
-
         }
     }
 
     return false;
 }
 
-static bool find_double_listen_window(bool bcommand, int16_t timeout) {
+static bool find_double_listen_window(bool bcommand) {
 
     // find two successive listen windows that indicate the beginning of
     // data transmission
@@ -451,7 +463,7 @@ static bool find_double_listen_window(bool bcommand, int16_t timeout) {
 
     int cnt_pulses = 0;
 
-    while (cnt_pulses < EM4X50_T_WAITING_FOR_DBLLIW && timeout--) {
+    while (cnt_pulses < EM4X50_T_WAITING_FOR_DBLLIW) {
 
         // identification of listen window is done via evaluation of
         // pulse lengths
@@ -508,7 +520,7 @@ static bool find_em4x50_tag(void) {
     // function is used to check wether a tag on the proxmark is an
     // EM4x50 tag or not -> speed up "lf search" process
 
-    return (find_single_listen_window(EM4X50_COMMAND_TIMEOUT));
+    return (find_single_listen_window());
 
 }
 
@@ -520,7 +532,7 @@ static bool request_receive_mode(void) {
 
     bool bcommand = true;
 
-    return find_double_listen_window(bcommand, EM4X50_COMMAND_TIMEOUT);
+    return find_double_listen_window(bcommand);
 }
 
 static bool check_ack(bool bliw) {
@@ -726,7 +738,7 @@ static bool standard_read(int *now) {
     uint8_t bits[EM4X50_TAG_WORD] = {0};
 
     // start with the identification of two succsessive listening windows
-    if (find_double_listen_window(false, EM4X50_COMMAND_TIMEOUT)) {
+    if (find_double_listen_window(false)) {
 
         // read and save words until following double listen window is detected
         while (get_word_from_bitstream(bits) == EM4X50_TAG_WORD)