Initial commit of fifo and i2c routines

i2cspi_BaS_gcc/sources/fifo.c

@@ -0,0 +1,109 @@
+/*
+ * fifo.c
+ *
+ * A general implementation of a fifo buffer
+ *
+ */
+
+#include <fifo.h>
+
+//This initializes the FIFO structure with the given buffer and size
+void fifo_init(fifo_t * f, char * buf, int size)
+{
+     f->head = 0;
+     f->tail = 0;
+     f->size = size;
+     f->buf = buf;
+}
+
+// Get one byte from the fifo buffer
+uint8_t fifo_get(fifo_t *f)
+{
+    uint8_t ch = 0;
+
+    if( f->tail != f->head && f->tail < f->size )
+    {
+        ch = f->buf[f->tail++];
+        if( f->tail >= f->size )
+            f->tail = 0;
+    }
+
+    return ch;
+}
+
+// Put one byte into the buffer
+void fifo_put(fifo_t *f, uint8_t byte)
+{
+    if( f->head == f->tail || f->head >= f->size )
+        return;
+    f->buf[f->head] = byte;
+    fifo_advance(f,&f->head);
+}
+
+void fifo_clear(fifo_t *f)
+{
+    f->head = f->tail = 0;
+}
+
+int fifo_used(fifo_t *f)
+{
+    if( f->head > f->tail )
+        return (f->head - f->tail);
+    return (f->size - f->tail + f->head);
+}
+
+int fifo_unused(fifo_t *f)
+{
+    if( f->head > f->tail )
+        return (f->size-f->head+f->tail);
+    return (f->tail-f->head);
+}
+
+int fifo_full(fifo_t *f)
+{
+    if( f->head+1 >= f->size )
+        return (f->tail == 0);
+    return (f->head+1 == f->tail);
+}
+
+int fifo_empty(fifo_t *f)
+{
+    return (f->head == f->tail);
+}
+
+void fifo_advance(fifo_t *f, int *ix)
+{
+    if( ++*ix > f->size )
+        *ix=0;
+}
+
+//This reads at most nbytes bytes from the FIFO
+//The number of bytes read is returned
+int fifo_read(fifo_t *f, char *buf, int nbytes){
+     int n = 0;
+
+     while( n < nbytes && !fifo_empty(f) )
+     {
+         n++;
+         *buf++ = f->buf[f->tail];
+         fifo_advance(f,&f->tail);
+     }
+
+     return n;
+}
+
+//This writes up to nbytes bytes to the FIFO
+//If the head runs in to the tail, not all bytes are written
+//The number of bytes written is returned
+int fifo_write(fifo_t *f, const char *buf, int nbytes){
+     int n = 0;
+
+     while( n < nbytes && !fifo_full(f) )
+     {
+         f->buf[f->head] = *buf++;
+         fifo_advance(f,&f->head);
+         n++;
+     }
+
+     return n;
+}