add pru asm timer

diff --git a/src/pru.S b/src/pru.S
new file mode 100644 (file)
index 0000000..dcc5493
--- /dev/null
+++ b/src/pru.S
@@ -0,0 +1,40 @@
+/* 
+ * Copyright (c) 2016, Ian Sutton <ian@kremlin.cc>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for
+ * any purpose with or without fee is hereby granted, provided that the
+ * above copyright notice and this permission notice appear in all
+ * copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+.origin 0
+.entrypoint START /* used by debugger only */
+
+#define PRU0_R31_VEC_VALID (1<<5)
+#define SIGNUM 3 /* corresponds to PRU_EVTOUT_0 */
+
+#define DELAY_SECONDS 5
+#define CLOCK 200000000
+#define CLOCKS_PER_LOOP 2
+#define DELAYCOUNT DELAY_SECONDS * CLOCK / CLOCKS_PER_LOOP
+
+START:
+       MOV     r1, DELAYCOUNT
+
+DELAY:
+       SUB     r1, r1, 1
+       QBNE    DELAY, r1, 0
+
+       /* intr */
+       MOV     R31.b0, PRU0_R31_VEC_VALID | SIGNUM
+       HALT
+