From 2259f32736353bac665a244fc82a6ceb84313319 Mon Sep 17 00:00:00 2001
From: David Thacher <davidethacher@gmail.com>
Date: Sat, 23 Sep 2023 14:43:44 -0400
Subject: [PATCH] #20 WIP

---
 LED_Matrix/lib/Serial/serial_uart/wip.cpp | 149 ++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 LED_Matrix/lib/Serial/serial_uart/wip.cpp

diff --git a/LED_Matrix/lib/Serial/serial_uart/wip.cpp b/LED_Matrix/lib/Serial/serial_uart/wip.cpp
new file mode 100644
index 00000000..a6243d4b
--- /dev/null
+++ b/LED_Matrix/lib/Serial/serial_uart/wip.cpp
@@ -0,0 +1,149 @@
+#include "pico/stdlib.h"
+#include <stdint.h>
+#include <algorithm>
+
+// Preamble must be half of packet
+struct Packet {
+    uint8_t preamble[32];
+    uint8_t inverse[16];
+    uint32_t length;
+    uint32_t command;
+    uint32_t marker;
+    uint32_t checksum;
+};
+
+static uint16_t index = 0;
+
+//uint8_t iterator(Packet *p1, Packet *p2, uint16_t i);
+
+void __attribute__ ((noinline)) other_task();
+void __attribute__ ((noinline)) task();
+
+int main(int argc, char **argv) {
+    int LED_PIN = 0;
+
+    gpio_init(LED_PIN);
+    gpio_set_dir(LED_PIN, GPIO_OUT);
+
+    while (1) {
+        gpio_put(LED_PIN, 1);
+        task();
+        gpio_put(LED_PIN, 0);
+        other_task();
+    }
+}
+
+
+constexpr uint8_t iterator(Packet *p1, Packet *p2, uint16_t i) {
+    if (i < sizeof(Packet)) {
+        uint8_t *ptr = (uint8_t *) p1;
+
+        return *(ptr + i);
+    }
+    else {
+        uint8_t *ptr = (uint8_t *) p2;
+        i -= sizeof(Packet);
+
+        return *(ptr + i);
+    }
+}
+
+bool search(Packet *p1, Packet *p2) {
+    int i, j;
+
+    // Look for start of preamble
+    for (i = std::max(index - 4, 0); i < std::min(index, (uint16_t) 4); i++) {
+        if (iterator(p1, p2, i) == 0x19)
+            break;
+    }
+
+    // Verify Preamble
+    for (j = index; j < (int) (index + sizeof(Packet::preamble) - i); j++) {
+        if (iterator(p1, p2, j) != 0x19)
+            return false;
+    }
+
+    j += 4;
+
+    // TODO: Verify checksum, inverse, marker
+
+    // Stay in phase or realign phase
+    index = i;
+
+    return true;
+}
+
+bool isNewFrame(Packet *p1, Packet *p2) {
+    uint8_t *ptr = (uint8_t *) p1;
+    
+    while (true) {
+        // Jump out if preamble not found in Packet
+        if (index >= sizeof(Packet)) {
+            index -= sizeof(Packet);
+            break;
+        }
+
+        // Spot check for preamble (fast reject/jump out)
+        if (*(ptr + index) == 0x19)
+            return search(p1, p2);
+        else
+            index += sizeof(Packet) / 4;
+    }
+
+    return false;
+}
+
+constexpr uint8_t rows = 3;
+constexpr uint8_t columns = 16;
+Packet array[columns][rows];
+volatile bool isReady = false;
+
+void reset_state_machine() {
+    // TODO    
+}
+
+void state_machine(Packet *p) {
+    // TODO
+}
+
+void flush_state_machine() {
+    // TODO
+}
+
+void task() {
+    static uint8_t last = rows;
+
+    if (isReady) {
+        // Handle boundary between rows
+        if (isNewFrame(&array[columns - 1][last], &array[0][(last + 1) % rows])) 
+            reset_state_machine();
+        state_machine(&array[columns - 1][last]);
+
+        // Advance to next row
+        last = (last + 1) % rows;
+        isReady = false;
+
+        // Handle columns in row
+        for (int i = 0; i < (columns - 1); i++) {
+            if (isNewFrame(&array[i][last], &array[i + 1][last])) 
+                reset_state_machine();
+
+            state_machine(&array[i][last]);
+        }
+
+        flush_state_machine();
+    }
+}
+
+void other_task() {
+    static uint8_t num = 0;
+
+    for (int i = 0; i < columns; i++) {
+        for (int j = 0; j < (int) sizeof(Packet::preamble); j++) {
+            array[i][num].preamble[j] = 0x19;
+        }
+    }
+
+    num = (num + 1) % rows;
+    isReady = true;
+}
\ No newline at end of file