From 5bb9cf38c84663713c178f54b684d40b6c00b11d Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Sun, 2 Apr 2017 20:33:49 -0700
Subject: [PATCH] cortexelf-v1: Add bit flipping array generator

Someone hooked up the data lines between the systems backwards, so we
get to swizzle the bits in software.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 src/cortexelf-v1/Makefile        |  7 +++++--
 src/cortexelf-v1/ao_flip_bits.5c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 src/cortexelf-v1/ao_flip_bits.5c

diff --git a/src/cortexelf-v1/Makefile b/src/cortexelf-v1/Makefile
index b491c2e4..77598dda 100644
--- a/src/cortexelf-v1/Makefile
+++ b/src/cortexelf-v1/Makefile
@@ -28,9 +28,9 @@ INC = \
 	ao_lisp.h \
 	ao_lisp_const.h \
 	ao_lisp_os.h \
+	ao_flip_bits.h \
 	Makefile
 
-
 #PROFILE=ao_profile.c
 #PROFILE_DEF=-DAO_PROFILE=1
 
@@ -123,7 +123,10 @@ distclean:	clean
 
 clean::
 	rm -f *.o $(PROGNAME)-*.elf $(PROGNAME)-*.ihx
-	rm -f ao_product.h
+	rm -f ao_product.h ao_flip_bits.h
+
+ao_flip_bits.h: ao_flip_bits.5c
+	nickle ao_flip_bits.5c > $@
 
 include ../lisp/Makefile-lisp
 
diff --git a/src/cortexelf-v1/ao_flip_bits.5c b/src/cortexelf-v1/ao_flip_bits.5c
new file mode 100644
index 00000000..26900893
--- /dev/null
+++ b/src/cortexelf-v1/ao_flip_bits.5c
@@ -0,0 +1,19 @@
+#!/usr/bin/nickle
+
+int flip_bits(int a)
+{
+	int result = 0;
+	for (int pos = 0; pos < 8; pos++)
+		if ((a & (1 << pos)) != 0)
+			result |= (1 << (7 - pos));
+	return result;
+}
+
+printf ("static uint8_t ao_flip_bits[256] = {\n");
+
+for (int i = 0; i < 256; i++) {
+	printf (" 0x%02x,", flip_bits(i));
+	if ((i & 0xf) == 0xf)
+		printf("\n");
+}
+printf("};\n");
-- 
2.30.2