From f21e9797a28b6f4eb84f6c3a74d3b64817abc42a Mon Sep 17 00:00:00 2001
From: jaseg <git@jaseg.de>
Date: Sun, 1 May 2022 17:24:19 +0200
Subject: Fix 8b10b encoding running disparity issues.

---
 driver_fw/main.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

(limited to 'driver_fw/main.c')

diff --git a/driver_fw/main.c b/driver_fw/main.c
index 30ff633..5123237 100644
--- a/driver_fw/main.c
+++ b/driver_fw/main.c
@@ -81,6 +81,20 @@ static void set_status_leds(uint8_t val) {
     *((volatile uint8_t *)&(SPI1->DR)) = val ^ 0x0f; /* Invert LEDs connected to VCC instead of GND */
 }
 
+static int flipbits10(int in) {
+    return
+        (in&0x200)>>9 |
+        (in&0x100)>>7 |
+        (in&0x080)>>5 |
+        (in&0x040)>>3 |
+        (in&0x020)>>1 |
+        (in&0x010)<<1 |
+        (in&0x008)<<3 |
+        (in&0x004)<<5 |
+        (in&0x002)<<7 |
+        (in&0x001)<<9;
+
+}
 
 int main(void) {
     /* Startup code */
@@ -194,7 +208,7 @@ int main(void) {
 
     /* Initialize AC protocol state machine in TIM3 ISR with the AC protocol comma */
     xfr_8b10b_encode_reset(&txstate.st);
-    txstate.current_symbol = xfr_8b10b_encode(&txstate.st, K28_1) | 1<<10;
+    txstate.current_symbol = flipbits10(xfr_8b10b_encode(&txstate.st, K28_1)) | 1<<10;
     /* The timer is still stopped. Start it by manually triggering an update event. */
     TIM3->EGR |= TIM_EGR_UG;
 
@@ -219,22 +233,21 @@ int main(void) {
     }
 }
 
-static int flipbits10(int in) {
-    return
-        (in&0x200)>>9 |
-        (in&0x100)>>7 |
-        (in&0x080)>>5 |
-        (in&0x040)>>3 |
-        (in&0x020)>>1 |
-        (in&0x010)<<1 |
-        (in&0x008)<<3 |
-        (in&0x004)<<5 |
-        (in&0x002)<<7 |
-        (in&0x001)<<9;
+#define BACKCHANNEL_INTERVAL 10
 
+__attribute__((__noreturn__)) void __assert_func (const char *, int, const char *, const char *){
+    asm volatile ("bkpt");
+    while (1);
 }
 
-#define BACKCHANNEL_INTERVAL 10
+int hamming_weight(int i) {
+    int r = 0;
+    for (int j = 0; j < 32; j ++) {
+        if (i < 0) r ++;
+        i <<= 1;
+    }
+    return r;
+}
 
 void TIM3_IRQHandler() {
     static int txpos = -1;
-- 
cgit