From 729f2a2c3ebfb2612d873caf453a1d7ca02180d9 Mon Sep 17 00:00:00 2001
From: dmlunar <root@lunar.sh>
Date: Wed, 22 Jan 2025 16:47:21 +0200
Subject: varpa: initial public commit

---
 firmware/src/peripheral/uart.c | 239 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 239 insertions(+)
 create mode 100644 firmware/src/peripheral/uart.c

(limited to 'firmware/src/peripheral/uart.c')

diff --git a/firmware/src/peripheral/uart.c b/firmware/src/peripheral/uart.c
new file mode 100644
index 0000000..defcf54
--- /dev/null
+++ b/firmware/src/peripheral/uart.c
@@ -0,0 +1,239 @@
+/**
+ * 
+ * Author: Dylan Muller
+ * Copyright (c) 2025 
+ * All rights reserved.
+ * 
+ * - Commercial/IP use prohibited.
+ * - Attribution required.
+ * See License.txt
+ *
+ */
+
+#include "setup.h"
+
+#include "peripheral/ring.h"
+#include "peripheral/uart.h"
+
+#include "status.h"
+#include "cmd.h"
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/atomic.h>
+#include <util/setbaud.h>
+
+extern t_system_status system_status;
+
+static int uart_putc(
+    char c,
+    FILE *stream
+)
+{
+    (void)stream;
+
+    if(uart_tx(c))
+        return _FDEV_EOF;
+    
+    return c;
+}
+
+static int uart_getc(
+    FILE *stream
+)
+{
+    uint8_t c;
+    (void)stream;
+
+    if(uart_rx(&c))
+        return _FDEV_EOF;
+    
+    return c;
+}
+
+FILE uart_out = FDEV_SETUP_STREAM(uart_putc, NULL, _FDEV_SETUP_WRITE);
+FILE uart_in = FDEV_SETUP_STREAM(NULL, uart_getc, _FDEV_SETUP_READ);
+
+static volatile ring_t uart_tx_ring;
+static volatile ring_t uart_rx_ring;
+
+static volatile uint8_t uart_tx_buf[UART_BUF_SIZE];
+static volatile uint8_t uart_rx_buf[UART_BUF_SIZE];
+
+void uart_init(void)
+{
+    uart_tx_ring = ring_init((uint8_t*)uart_tx_buf, UART_BUF_SIZE - 1);
+    uart_rx_ring = ring_init((uint8_t*)uart_rx_buf, UART_BUF_SIZE - 1);
+    
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+    UCSR0B |= (1 << RXCIE0) | (1 << RXEN0) | (1 << TXEN0);
+    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
+    
+    stdout = &uart_out;
+    stdin = &uart_in;
+}
+
+bool uart_tx(
+    uint8_t data
+)
+{
+    bool ret;
+    
+    while(ring_is_full(uart_tx_ring));
+    
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+        ret = ring_push((ring_t*)&uart_tx_ring, data);
+    }
+
+    if(!ret)
+        UCSR0B |= (1 << UDRIE0);
+    
+    return ret;
+}
+
+bool uart_rx(
+    uint8_t* data
+)
+{
+    bool ret;
+    
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+        ret = ring_pop((ring_t*)&uart_rx_ring, data);
+    }
+    
+    return ret;
+}
+
+size_t uart_tx_burst(
+    uint8_t *data,
+    size_t size
+)
+{
+    size_t i = 0;
+    
+    while(i<size && !uart_tx(*data++))
+        i++;
+    
+    return i;
+}
+
+size_t uart_rx_burst(
+    uint8_t* data,
+    size_t len
+)
+{
+    size_t i = 0;
+    
+    while(i<len && !uart_rx(data++))
+        i++;
+    
+    return i;
+}
+
+size_t uart_tx_available(void)
+{
+    size_t ret;
+    
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+        ret = ring_push_available(uart_tx_ring);
+    }
+    
+    return ret;
+}
+
+size_t uart_rx_available(void)
+{
+    size_t ret;
+    
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+        ret = ring_pop_available(uart_rx_ring);
+    }
+    
+    return ret;
+}
+
+bool uart_rx_peek(
+    uint8_t *data
+)
+{
+    bool ret;
+    
+    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+    {
+        ret = ring_peek((ring_t*)&uart_rx_ring, data);
+    }
+    
+    return ret;
+}
+
+void uart_tx_flush(void)
+{
+    bool empty;
+    do
+    {
+        ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
+        {
+            empty = ring_is_empty(uart_tx_ring);
+        }
+    } while(!empty);
+}
+
+char *uart_ngets(char *s, size_t n)
+{
+    uint8_t c;
+    static size_t i = 0;
+    
+    
+    while(!uart_rx(&c))
+    {
+        s[i++] = c;
+        
+        if(c == '\n' || i >= n-1)
+        {
+            s[i] = '\0';
+            i = 0;
+            
+            return s;
+        }
+    }
+    
+    return NULL;
+}
+
+ISR(USART_UDRE_vect)
+{
+    uint8_t c;
+    
+    if(!ring_pop((ring_t*)&uart_tx_ring, &c))
+        UDR0 = c;
+
+    else
+        UCSR0B &= ~(1 << UDRIE0);
+}
+
+ISR(USART_RX_vect)
+{
+    if (system_status.status == SYSTEM_STATUS_BUSY)
+    {
+        // system busy.. lock now!
+        CMD_ERROR("SYSTEM BUSY");
+        system_status.status = SYSTEM_STATUS_LOCKED;
+    }
+
+    if (system_status.status != SYSTEM_STATUS_LOCKED)
+    {
+        #ifdef UART_OVERWRITE
+            ring_push_over((ring_t*)&uart_rx_ring, UDR0);
+        #else
+            ring_push((ring_t*)&uart_rx_ring, UDR0);
+        #endif
+    }
+    else{
+        (uint8_t)UDR0;
+    }
+}
-- 
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