From 58414f713ffeb89684711ea376636674b0f691f4 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris@lulabs.net>
Date: Thu, 25 Jun 2020 07:06:57 -0500
Subject: [PATCH] add comment and sim build rule

---
 Makefile    | 3 +++
 mandelsim.c | 3 +++
 2 files changed, 6 insertions(+)
 mode change 100644 => 100755 Makefile

diff --git a/Makefile b/Makefile
old mode 100644
new mode 100755
index cd766fa..b7b04ce
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,9 @@ PART = xc3s1200e-fg320-5
 
 all: fpga_target
 
+sim: mandelsim.c
+	gcc -O3 -lSDL -o mandelsim mandelsim.c -march=pentium3
+
 BITGEN_OPTS = \
 	-w \
 	-g DebugBitstream:No \
diff --git a/mandelsim.c b/mandelsim.c
index 16bdf46..2ce2feb 100644
--- a/mandelsim.c
+++ b/mandelsim.c
@@ -5,6 +5,9 @@
 #define YRES 480
 #define MAX_ITER 66
 #define MAXNUM 0x8000
+
+/* be sure to change the number of bits in the multiplier when doing this
+ * bits > 14 need extension of num_t to unsigned int */
 #define BITS 14
 #define BAIL (1 << (BITS + 1))
 #define BAIL_A (1 << BITS)
-- 
2.43.0