From 6e2ab11578a1f3a07933b8f712b7e20413506ae4 Mon Sep 17 00:00:00 2001
From: Dreaded_X <tim.huizinga@gmail.com>
Date: Sat, 16 Jan 2021 01:34:57 +0100
Subject: [PATCH] Added hardware random option and added function to set seed

---
 Makefile         |  2 +-
 include/random.h |  8 ++++++++
 src/random.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/random.s     | 31 -------------------------------
 4 files changed, 57 insertions(+), 32 deletions(-)
 create mode 100644 src/random.c
 delete mode 100644 src/random.s

diff --git a/Makefile b/Makefile
index 2399ec0..01be640 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ ASFLAGS = -plosgff
 SRC = \
 src/crt0.s \
 src/bios.s \
-src/random.s \
+src/random.c \
 src/console.c \
 
 OBJ_1 = $(notdir $(SRC:.c=.rel))
diff --git a/include/random.h b/include/random.h
index 8406e3d..02f36fa 100644
--- a/include/random.h
+++ b/include/random.h
@@ -1,3 +1,11 @@
 #include "types.h"
 
+// Get a pseudo random number
 uint8_t random();
+// Set the seed for the random number generator
+void random_set_seed(uint8_t seed);
+
+// Get a random number from hardware
+uint8_t random_hw();
+
+
diff --git a/src/random.c b/src/random.c
new file mode 100644
index 0000000..63d6d91
--- /dev/null
+++ b/src/random.c
@@ -0,0 +1,48 @@
+#include "random.h"
+
+uint8_t random_seed;
+
+// Fast RND
+//
+// An 8-bit pseudo-random number generator,
+// using a similar method to the Spectrum ROM,
+// - without the overhead of the Spectrum ROM.
+//
+// R = random number seed
+// an integer in the range [1, 256]
+//
+// R -> (33*R) mod 257
+//
+// S = R - 1
+// an 8-bit unsigned integer
+
+uint8_t random()  __naked {
+	__asm
+		ld a, (_random_seed)
+		ld b, a 
+
+		rrca ; multiply by 32
+		rrca
+		rrca
+		xor #0x1f
+
+		add a, b
+		sbc a, #255 ; carry
+
+		ld (_random_seed), a
+		ld l, a
+		ret
+	__endasm;
+}
+
+void random_set_seed(uint8_t seed) {
+	random_seed = seed;
+}
+
+uint8_t random_hw() __naked {
+	__asm
+		in a, (0x09)
+		ld l, a
+		ret
+	__endasm;
+}
diff --git a/src/random.s b/src/random.s
deleted file mode 100644
index b504040..0000000
--- a/src/random.s
+++ /dev/null
@@ -1,31 +0,0 @@
-; Fast RND
-;
-; An 8-bit pseudo-random number generator,
-; using a similar method to the Spectrum ROM,
-; - without the overhead of the Spectrum ROM.
-;
-; R = random number seed
-; an integer in the range [1, 256]
-;
-; R -> (33*R) mod 257
-;
-; S = R - 1
-; an 8-bit unsigned integer
-
-	.area _CODE
-
-_random::
-	ld a, (_random_seed)
-	ld b, a 
-
-	rrca ; multiply by 32
-	rrca
-	rrca
-	xor #0x1f
-
-	add a, b
-	sbc a, #255 ; carry
-
-	ld (_random_seed), a
-	ld l, a
-	ret