Optimisations to xud select cases

examples/xua_lite_example/src/fifo_impl.h

@@ -43,6 +43,24 @@ static inline fifo_ret_t fifo_block_push(volatile mem_fifo_t * unsafe fifo, int
     }
 }
 
+#pragma unsafe arrays
+static inline fifo_ret_t fifo_block_push_short_pairs(volatile mem_fifo_t * unsafe fifo, short data[], unsigned n) {
+    unsafe{
+        //check there is a block of space large enough
+        unsigned space_remaining = fifo->size - fifo_get_fill(fifo) - 1;
+        if (n > space_remaining) {
+            return FIFO_FULL;
+        }
+        for (int i = 0; i < n; i++){
+            unsigned next_idx = fifo->write_idx + 1;
+            if (next_idx == fifo->size) next_idx = 0; //Check for wrap
+            fifo->data_base_ptr[fifo->write_idx] = data[i] << 16;
+            fifo->write_idx = next_idx;
+        }
+        return FIFO_SUCCESS;
+    }
+}
+
 #pragma unsafe arrays
 static inline fifo_ret_t fifo_block_pop(volatile mem_fifo_t * unsafe fifo, int data[], unsigned n) {
     unsafe{
@@ -59,6 +77,21 @@ static inline fifo_ret_t fifo_block_pop(volatile mem_fifo_t * unsafe fifo, int d
     }
 }
 
+#pragma unsafe arrays
+static inline fifo_ret_t fifo_block_pop_short_pairs(volatile mem_fifo_t * unsafe fifo, short data[], unsigned n) {
+    unsafe{
+        //Check we have a block big enough to send
+        if (n > fifo_get_fill(fifo)){
+            return FIFO_EMPTY;
+        }
+        for (int i = 0; i < n; i++){
+            data[i] = fifo->data_base_ptr[fifo->read_idx] >> 16;
+            fifo->read_idx++;
+            if (fifo->read_idx == fifo->size) fifo->read_idx = 0; //Check for wrap
+        }
+        return FIFO_SUCCESS;
+    }
+}
 
 //Version of above that returns fill level relative to half full
 static inline int fifo_get_fill_relative_half(volatile mem_fifo_t * unsafe fifo){