From 25e6afd831b94b9735cc6691ee19c8edc921aca7 Mon Sep 17 00:00:00 2001
From: root <root@lab.panaceas.james.local>
Date: Sun, 8 Apr 2018 01:14:30 +0100
Subject: working decoding

---
 app/msf.c | 226 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 226 insertions(+)
 create mode 100644 app/msf.c

(limited to 'app/msf.c')

diff --git a/app/msf.c b/app/msf.c
new file mode 100644
index 0000000..392bfe7
--- /dev/null
+++ b/app/msf.c
@@ -0,0 +1,226 @@
+#include "project.h"
+
+#define P1 (GPIO1)
+#define P1_PORT GPIOB
+
+#define T (GPIO0)
+#define T_PORT GPIOB
+
+static uint8_t bitsa[60], bitsb[60];
+
+static int time_known;
+static int check_parity (uint8_t *d, unsigned s, unsigned e, uint8_t p)
+{
+  unsigned i;
+
+  for (i = s; i <= e; ++i)
+    p ^= d[i];
+
+  return !p;
+}
+
+
+static unsigned bcd (uint8_t *d, unsigned s, unsigned e)
+{
+  unsigned ret = 0, c, b, i;
+
+  for (i = e, c = 1, b = 0; i >= s; --i, b++) {
+
+    if (d[i]) ret += c;
+
+
+    switch (b & 3) {
+    case 0:
+    case 1:
+    case 2:
+      c <<= 1;
+      break;
+
+    default:
+      c >>= 3;
+      c *= 10;
+    }
+  }
+
+  return ret;
+}
+
+
+
+static int check_min_ident (uint8_t *i)
+{
+  if (i[0]) return 1;
+
+  if (!i[1]) return 1;
+
+  if (!i[2]) return 1;
+
+  if (!i[3]) return 1;
+
+  if (!i[4]) return 1;
+
+  if (!i[5]) return 1;
+
+  if (!i[6]) return 1;
+
+  if (i[7]) return 1;
+
+  return 0;
+}
+
+
+
+static void process_bits (uint64_t abs)
+{
+  UTC u;
+  EPOCH msf_time;
+
+
+  if (check_min_ident (&bitsa[52])) return;
+
+  if (check_parity (bitsa, 17, 24, bitsb[54])) return;
+
+  if (check_parity (bitsa, 25, 35, bitsb[55])) return;
+
+  if (check_parity (bitsa, 36, 38, bitsb[56])) return;
+
+  if (check_parity (bitsa, 39, 51, bitsb[57])) return;
+
+  u.jday = 0;
+  u.year = bcd (bitsa, 17, 24);
+  u.month = bcd (bitsa, 25, 29);
+  u.mday = bcd (bitsa, 30, 35);
+  u.hour = bcd (bitsa, 39, 44);
+  u.minute = bcd (bitsa, 45, 51);
+  u.second = 59;
+  u.nanosecond = 0;
+
+  /* This is always valid a check_min_ident will fail for leap seconds*/
+
+  msf_time = time_utc_to_epoch (u);
+  msf_time.s -= 59;
+
+  pll_set_offset (msf_time, abs);
+  time_known = 1;
+
+  printf ("Next minute is: %02d-%02d-%02d %02d:%02d\r\n", u.year, u.month, u.mday, u.hour, u.minute);
+  time_print_epoch (msf_time);
+}
+
+
+static void report_bits (uint64_t abs, int second, int a, int b)
+{
+  if ((!second) || (second > 59)) return;
+
+  bitsa[second] = a;
+  bitsb[second] = b;
+
+  if (second == 59) process_bits (abs);
+
+}
+
+static void report_time (uint64_t abs)
+{
+  EPOCH e = pll_decompose (abs);
+  time_print_epoch (e);
+  printf ("%d\r\n", (unsigned) e.s);
+}
+
+void exti0_isr (void)
+{
+  static uint32_t last_0;
+  static uint32_t last_1;
+  static uint32_t last_s;
+  static int second, bita, bitb, had_m;
+
+  uint32_t now = SCS_DWT_CYCCNT;
+  uint64_t abs;
+
+  uint32_t pulse_w, offset;
+  int is_s = 0;
+  int v;
+
+  nvic_disable_irq (NVIC_EXTI0_IRQ);
+  exti_reset_request (EXTI0);
+
+  v = !!gpio_get (T_PORT, T);
+
+  if (v) {
+    pulse_w = now - last_0;
+    pulse_w /= (HZ / 1000);
+
+    if (pulse_w > 300)  {
+      last_s = now;
+      is_s = 1;
+    }
+
+    last_1 = now;
+
+  } else {
+    pulse_w = now - last_1;
+    pulse_w /= (HZ / 1000);
+
+    if (pulse_w > 400)  {
+      had_m = 1;
+      second = 0;
+    }
+
+    last_0 = now;
+  }
+
+  offset = now - last_s;
+  offset /= (HZ / 1000);
+
+
+  if (is_s) {
+    abs = abs_extend (now);
+    pll_dispatch (abs);
+
+    if (had_m) {
+      report_bits (abs, second, bita, bitb);
+      second++;
+
+    }
+
+    if (time_known)
+      report_time (abs);
+  }
+
+
+
+  if (!v) { /* 1->0 transition */
+    if (offset < 150) {
+      bita = 0;
+      bitb = 0;
+    }
+
+    if (offset < 250)
+      bitb = 0;
+  } else { /* 0->1  transition*/
+    if (is_s) {
+      bita = 1;
+      bitb = 1;
+    } else if (offset < 250)
+      bitb = 1;
+  }
+
+
+
+  nvic_enable_irq (NVIC_EXTI0_IRQ);
+}
+
+void
+radio_init (void)
+{
+  MAP_INPUT (T);
+  MAP_OUTPUT_PP (P1);
+
+  gpio_clear (P1_PORT, P1);
+
+  exti_select_source (EXTI0, T_PORT);
+  exti_set_trigger (EXTI0, EXTI_TRIGGER_BOTH);
+  exti_enable_request (EXTI0);
+  nvic_enable_irq (NVIC_EXTI0_IRQ);
+}
+
+
-- 
cgit v1.2.3