Plug in variable size queue implementation for saving buffer space in iAP.

module_usb_midi/src/queue.c

@@ -1,22 +1,49 @@
 #include <stdio.h>
 #include "queue.h"
 
+// Queue implementation
+//  Offers no protection against adding when full or dequeueing when empty.
+//  Uses read and write counts for pointers to distinguish full and empty cases.
+//  Works from c and xc
+//  Must allocate the memory outside of this and pass it in to init_queue so can statically allocate
+//  Must work for different element sizes
+
 // This presumes that the xc compiler will not re-use the mem passed to init_queue
-void init_queue(queue *q, unsigned arr[], int size) {
+void init_queue(queue *q, unsigned char arr[], int size, int element_size) {
    q->rdptr = 0;
    q->wrptr = 0;
    q->data = (uintptr_t)arr;
-   q->size = size; // presume that size is power of two
+   q->size = size; // in items, presume that size is power of two
+   q->element_size = element_size; // The size of each element in bytes
    q->mask = size - 1;
 }
 
 extern inline void enqueue(queue *q, unsigned value) {
-   ((unsigned *)q->data)[q->wrptr & q->mask] = value;
+   switch (q->element_size) {
+      case 4:
+         ((unsigned *)q->data)[q->wrptr & q->mask] = value;
+         break;
+      case 1:
+         ((unsigned char *)q->data)[q->wrptr & q->mask] = (unsigned char)value;
+         break;
+      default:
+         break;
+   }
    q->wrptr++;
 }
 
 extern inline unsigned dequeue(queue *q) {
-   unsigned retval = ((unsigned *)q->data)[q->rdptr & q->mask];
+   unsigned retval;
+   switch (q->element_size) {
+      case 4:
+         retval = ((unsigned *)q->data)[q->rdptr & q->mask];
+         break;
+      case 1:
+         retval = ((unsigned char *)q->data)[q->rdptr & q->mask];
+         break;
+      default:
+         break;
+   }
    q->rdptr++;
    return retval;
 }
@@ -41,7 +68,17 @@ extern inline int space(queue *q) {
 
 void dump(queue *q) {
    for (int i = q->rdptr; i != q->wrptr; i++) {
-      printf("a[%d] = %d\n", i & q->mask, ((unsigned *)q->data)[i & q->mask]);
+      switch (q->element_size) {
+         case 4:
+            printf("a[%d] = %d\n", i & q->mask, ((unsigned *)q->data)[i & q->mask]);
+            break;
+         case 1:
+            printf("a[%d] = %d\n", i & q->mask, ((unsigned char *)q->data)[i & q->mask]);
+            break;
+         default:
+            break;
+      }
    }
 }
 
+

module_usb_midi/src/queue.h

@@ -9,10 +9,11 @@ typedef struct queue {
    int rdptr; // Using absolute indices which count reads and writes so this needs to be considered when accessing.
    int wrptr;
    int size;
+   int element_size;
    int mask;
 } queue;
 
-void init_queue(REFERENCE_PARAM(queue, q), unsigned arr[], int size);
+void init_queue(REFERENCE_PARAM(queue, q), unsigned char arr[], int size, int element_size);
 void enqueue(REFERENCE_PARAM(queue, q), unsigned value);
 unsigned dequeue(REFERENCE_PARAM(queue, q));
 int isempty(REFERENCE_PARAM(queue, q));

module_usb_midi/src/usb_midi.xc

@@ -1,6 +1,7 @@
 #include <xs1.h>
 #include <xclib.h>
 #include <print.h>
+#include <stdint.h>
 #include "usb_midi.h"
 #include "midiinparse.h"
 #include "midioutparse.h"
@@ -91,7 +92,7 @@ chanend c_iap, chanend ?c_i2c // iOS stuff
 
   // One place buffer for data going out to host
   queue midi_to_host_fifo;
-  unsigned midi_to_host_fifo_arr[1];
+  unsigned char midi_to_host_fifo_arr[4]; // Used for 32bit USB MIDI events
 
   unsigned outputting_symbol, outputted_symbol;
 
@@ -99,14 +100,14 @@ chanend c_iap, chanend ?c_i2c // iOS stuff
 
   // the symbol fifo (to go out of uart)
   queue symbol_fifo;
-  unsigned symbol_fifo_arr[USB_MIDI_DEVICE_OUT_FIFO_SIZE];
+  unsigned char symbol_fifo_arr[USB_MIDI_DEVICE_OUT_FIFO_SIZE * 4]; // Used for 32bit USB MIDI events
 
   unsigned rxPT, txPT;
   int midi_from_host_overflow = 0;
 
   //configure_clock_rate(clk_midi, 100, 1);
-  init_queue(symbol_fifo, symbol_fifo_arr, USB_MIDI_DEVICE_OUT_FIFO_SIZE);
+  init_queue(symbol_fifo, symbol_fifo_arr, USB_MIDI_DEVICE_OUT_FIFO_SIZE, 4);
-  init_queue(midi_to_host_fifo, midi_to_host_fifo_arr, 1);
+  init_queue(midi_to_host_fifo, midi_to_host_fifo_arr, 1, 4);
 
   configure_out_port_no_ready(p_midi_out, clk_midi, 1);
   configure_in_port(p_midi_in, clk_midi);