# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1539863781 -7200
# Node ID 412fcc6d7b0cac8fb94a14228e53422ac8699b43
# Parent  e2302e08b02e28cdc7c10379839e54cf0f9bd1b4
Test with higher-priority interrupt, disabling DMA, due to instability.

diff -r e2302e08b02e -r 412fcc6d7b0c main.c
--- a/main.c	Thu Oct 18 13:36:42 2018 +0200
+++ b/main.c	Thu Oct 18 13:56:21 2018 +0200
@@ -64,16 +64,16 @@
 
     init_dma();
     dma_init(0, 0, 3);
-    dma_set_interrupt(0, U1RX, 1);
+    /* dma_set_interrupt(0, U1RX, 1); */
     dma_set_transfer(0, PHYSICAL(message), sizeof(message) - 1,
                         HW_PHYSICAL(UART_REG(1, UxTXREG)), 1,
                         1);
     dma_on(0);
 
-    /* Set UART interrupt priority below CPU priority. */
+    /* Set UART with interrupt. */
 
     uart_init(1, 115200);
-    uart_init_interrupt(1, UxRIF, 1, 3);
+    uart_init_interrupt(1, UxRIF, 4, 3);
     uart_on(1);
 
     interrupts_on();
@@ -90,16 +90,19 @@
 {
     /* Check for a UART receive interrupt condition (UxRIF). */
 
-    if (REG(UARTIFS) & UART_INT_FLAGS(1, UxRIF))
+    uint32_t ifs = REG(UARTIFS) & UART_INT_FLAGS(1, UxRIF);
+
+    if (ifs)
     {
+        /* Clear the UART interrupt condition. */
+
+        CLR_REG(UARTIFS, ifs);
+
         /* Write the received data back. */
 
         while (REG(UART_REG(1, UxSTA)) & 1)
             uart_write((char) REG(UART_REG(1, UxRXREG)));
 
-        /* Clear the UART interrupt condition. */
-
-        CLR_REG(UARTIFS, UART_INT_FLAGS(1, UxRIF));
         INV_REG(PORTA, 1 << 2);
     }
 }