Initial push

1 files changed, 246 insertions, 0 deletions

diff --git a/stacks/max25-bcpr/src/bcpr_ser12.c b/stacks/max25-bcpr/src/bcpr_ser12.c
new file mode 100644
index 0000000..32091e0
--- /dev/null
+++ b/stacks/max25-bcpr/src/bcpr_ser12.c
@@ -0,0 +1,246 @@
+#include "bcpr/bcpr_ser12.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+void bcpr_ser12_set_mode(bcpr_ser12_t *s, const char *mode, unsigned *baud_out)
+{
+    unsigned baud = 1200;
+    if (mode && strncmp(mode, "ser", 3) == 0) {
+        unsigned n = (unsigned)strtoul(mode + 3, NULL, 10);
+        if (n >= 3 && n <= 48) {
+            baud = n * 100u;
+        }
+    }
+    if (baud_out) {
+        *baud_out = baud;
+    }
+    s->baud = baud;
+    s->baud_us = 1000000u / baud;
+    if (mode && strchr(mode, '*')) {
+        s->opt_dcd = 0;
+    } else if (mode && strchr(mode, '+')) {
+        s->opt_dcd = -1;
+    } else {
+        s->opt_dcd = 1;
+    }
+}
+
+void bcpr_ser12_init(bcpr_ser12_t *s, unsigned baud, int opt_dcd)
+{
+    memset(s, 0, sizeof(*s));
+    s->baud = baud ? baud : 1200;
+    s->baud_us = 1000000u / s->baud;
+    s->opt_dcd = opt_dcd;
+    s->shreg = 0x10000;
+    s->dcd_sum0 = 2;
+    s->dcd_time = 120;
+    s->cal_mode = BCPR_CAL_OFF;
+    /* FlexNet SER12.doc defaults until bcpr_ser12_set_ptt_wd(). */
+    s->ptt_wd = 1;
+    s->ptt_wd_key_us = 14500u * 1000u;
+    s->ptt_wd_pause_us = 500u * 1000u;
+}
+
+void bcpr_ser12_set_ptt_wd(bcpr_ser12_t *s, int enable, int key_ms, int pause_ms)
+{
+    if (!s) {
+        return;
+    }
+    s->ptt_wd = enable ? 1 : 0;
+    if (key_ms < 1000) {
+        key_ms = 1000;
+    }
+    if (pause_ms < 50) {
+        pause_ms = 50;
+    }
+    s->ptt_wd_key_us = (unsigned)key_ms * 1000u;
+    s->ptt_wd_pause_us = (unsigned)pause_ms * 1000u;
+    s->ptt_wd_pausing = 0;
+    s->ptt_wd_phase_start_us = 0;
+}
+
+void bcpr_ser12_force_unkey(bcpr_ser12_t *s)
+{
+    if (!s) {
+        return;
+    }
+    s->ptt_hw = 0;
+    s->ptt_wd_pausing = 0;
+    s->ptt_wd_phase_start_us = 0;
+    s->txshreg = 0;
+}
+
+void bcpr_ser12_set_cal(bcpr_ser12_t *s, int cal_mode)
+{
+    if (!s) {
+        return;
+    }
+    if (cal_mode < BCPR_CAL_OFF || cal_mode > BCPR_CAL_ALT) {
+        cal_mode = BCPR_CAL_OFF;
+    }
+    s->cal_mode = cal_mode;
+    if (cal_mode != BCPR_CAL_OFF) {
+        s->ptt_hw = 1;
+        if (cal_mode == BCPR_CAL_HIGH) {
+            s->tx_bit = 1;
+        } else if (cal_mode == BCPR_CAL_LOW) {
+            s->tx_bit = 0;
+        } else {
+            s->tx_bit = 0; /* alt starts low, toggles each tick */
+        }
+        s->txshreg = 1;
+        s->ptt_wd_pausing = 0;
+        s->ptt_wd_phase_start_us = 0;
+    }
+}
+
+/*
+ * FlexNet SER12.doc / PAR96: during long calibrate, drop PTT every ~14.5 s for
+ * ~500 ms so the radio PTT watchdog can discharge. Mirror for --cal and any
+ * sustained key. Logical ptt_hw stays 1 (keep baud divisor / telemetry); only
+ * MCR RTS is cleared for the pause window.
+ */
+static void ser12_apply_ptt_wd(bcpr_ser12_t *s, int *mcr_out, unsigned now_us)
+{
+    unsigned elapsed;
+
+    if (!s->ptt_wd || !s->ptt_hw) {
+        s->ptt_wd_pausing = 0;
+        s->ptt_wd_phase_start_us = 0;
+        return;
+    }
+    if (s->ptt_wd_phase_start_us == 0) {
+        s->ptt_wd_phase_start_us = now_us ? now_us : 1u;
+        s->ptt_wd_pausing = 0;
+        return;
+    }
+    elapsed = now_us - s->ptt_wd_phase_start_us;
+    if (!s->ptt_wd_pausing) {
+        if (elapsed >= s->ptt_wd_key_us) {
+            s->ptt_wd_pausing = 1;
+            s->ptt_wd_phase_start_us = now_us ? now_us : 1u;
+            *mcr_out = 0x0d; /* RTS clear — PTT off */
+        }
+        return;
+    }
+    /* In pause: force idle MCR regardless of cal/HDLC bit. */
+    *mcr_out = 0x0d;
+    if (elapsed >= s->ptt_wd_pause_us) {
+        s->ptt_wd_pausing = 0;
+        s->ptt_wd_phase_start_us = now_us ? now_us : 1u;
+        /* Next tick restores keyed MCR from cal/HDLC path. */
+    }
+}
+
+static void ser12_rx(bcpr_ser12_t *s, bcpr_hdlc_t *h, unsigned curs,
+                     unsigned now_us)
+{
+    int timediff;
+    int bdus8 = (int)(s->baud_us >> 3);
+    int bdus4 = (int)(s->baud_us >> 2);
+    int bdus2 = (int)(s->baud_us >> 1);
+
+    timediff = (int)(now_us - s->pll_time);
+    /* wrap handling for us modulo ~1s window */
+    while (timediff >= 500000) {
+        timediff -= 1000000;
+    }
+    while (timediff <= -500000) {
+        timediff += 1000000;
+    }
+    while (timediff >= bdus2) {
+        timediff -= (int)s->baud_us;
+        s->pll_time += s->baud_us;
+        s->dcd_time--;
+        if (s->shreg & 1) {
+            bcpr_hdlc_putbits(h, (s->shreg >> 1) ^ 0xffffu);
+            s->shreg = 0x10000;
+        }
+        s->shreg >>= 1;
+    }
+    if (s->dcd_time <= 0) {
+        if (!s->opt_dcd) {
+            h->dcd = (s->dcd_sum0 + s->dcd_sum1 + s->dcd_sum2) < 0;
+        }
+        s->dcd_sum2 = s->dcd_sum1;
+        s->dcd_sum1 = s->dcd_sum0;
+        s->dcd_sum0 = 2;
+        s->dcd_time += 120;
+    }
+    if (s->last_rxbit != (unsigned char)curs) {
+        s->last_rxbit = (unsigned char)curs;
+        s->shreg |= 0x10000;
+        if (timediff > 0) {
+            s->pll_time += (unsigned)bdus8;
+        } else {
+            s->pll_time += 1000000u - (unsigned)bdus8;
+        }
+        if (abs(timediff) > bdus4) {
+            s->dcd_sum0 += 4;
+        } else {
+            s->dcd_sum0--;
+        }
+    }
+    while (s->pll_time >= 1000000u) {
+        s->pll_time -= 1000000u;
+    }
+}
+
+void bcpr_ser12_tick(bcpr_ser12_t *s, bcpr_hdlc_t *h, int cts, int *mcr_out,
+                     int *do_thr00, unsigned now_us)
+{
+    *do_thr00 = 1;
+
+    /* DOS cal.exe: continuous PTT + sticky/toggle DTR; no HDLC. */
+    if (s->cal_mode != BCPR_CAL_OFF) {
+        s->ptt_hw = 1;
+        if (s->cal_mode == BCPR_CAL_HIGH) {
+            s->tx_bit = 1;
+        } else if (s->cal_mode == BCPR_CAL_LOW) {
+            s->tx_bit = 0;
+        } else {
+            s->tx_bit = (unsigned char)!s->tx_bit;
+        }
+        *mcr_out = 0x0e | (!!s->tx_bit);
+        ser12_apply_ptt_wd(s, mcr_out, now_us);
+        return;
+    }
+
+    /*
+     * While PTT: skip Soft-DCD RX PLL — PC-COM charge-pump needs unbroken
+     * THR 0x00 @ baud; RX work causes multi-ms TXD gaps → underpowered AFSK.
+     */
+    if (!s->ptt_hw) {
+        ser12_rx(s, h, cts ? 1u : 0u, now_us);
+    }
+
+    if (s->ptt_hw) {
+        *mcr_out = 0x0e | (!!s->tx_bit);
+    } else {
+        *mcr_out = 0x0d;
+    }
+
+    if (s->ptt_hw) {
+        if (s->txshreg <= 1) {
+            s->txshreg = 0x10000u | bcpr_hdlc_getbits(h);
+            if (!bcpr_hdlc_ptt(h)) {
+                s->ptt_hw = 0;
+                *mcr_out = 0x0d;
+                ser12_apply_ptt_wd(s, mcr_out, now_us);
+                return;
+            }
+        }
+        s->tx_bit = (unsigned char)(!(s->tx_bit ^ (s->txshreg & 1)));
+        s->txshreg >>= 1;
+    } else {
+        bcpr_hdlc_arbitrate(h);
+        if (bcpr_hdlc_ptt(h)) {
+            s->txshreg = 1;
+            s->ptt_hw = 1;
+        }
+    }
+    bcpr_hdlc_transmitter(h);
+    ser12_apply_ptt_wd(s, mcr_out, now_us);
+    /* Receiver drain is owned by bcpr_engine (RX callback). */
+}