From a5d7e68af96d9b62821d8fd47f5039c5bae5d421 Mon Sep 17 00:00:00 2001
From: Reiner Herrmann <reiner@reiner-h.de>
Date: Fri, 10 Feb 2012 14:25:38 +0100
Subject: added original sam_player code

---
 c64/sid.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 c64/sid.c

(limited to 'c64/sid.c')

diff --git a/c64/sid.c b/c64/sid.c
new file mode 100644
index 0000000..845f799
--- /dev/null
+++ b/c64/sid.c
@@ -0,0 +1,91 @@
+// sid.c
+//
+// 20060803 Markku Alén
+
+#include "sid.h"
+#include "c64.h"
+
+static int record_init;
+static unsigned int record_freq;
+static unsigned char *record_buffer;
+static unsigned int record_max_len;
+static unsigned int record_index;
+
+void start_record(unsigned int frequency, unsigned char *wave_buf, unsigned int wave_max_len)
+{
+	record_init = 1;
+	record_freq = frequency;
+	record_buffer = wave_buf;
+	record_max_len = wave_max_len;
+	record_index = 0;
+}
+
+unsigned int stop_record(void)
+{
+	unsigned int len;
+	len = record_index;
+	record_freq = 0;
+	record_buffer = 0;
+	record_max_len = 0;
+	record_index = 0;
+	return len;
+}
+
+static void record(unsigned int counter, unsigned int sample)
+{
+	static unsigned int last_counter;
+	static unsigned int last_sample;
+	unsigned int elapsed;
+	if(record_init)
+	{
+		record_init = 0;
+		last_counter = counter;
+	}
+	elapsed = ((record_freq * (counter - last_counter)) + (F_CPU / 2)) / F_CPU;
+	while(elapsed-- > 0)
+	{
+		if(record_index < record_max_len)
+			record_buffer[record_index] = sample;
+		record_index += 1;
+	}
+	last_counter = counter;
+}
+
+static int volume;
+
+static unsigned char regs[32];
+
+void sid_init(void)
+{
+	int i;
+	for(i = sizeof(regs);i-- > 0;)
+		regs[i] = 0x00;
+	(void)stop_record();
+	volume = 0;
+}
+
+int sid_read(int address)
+{
+	switch(address & 0x001f)
+	{
+	case 0x0018:
+		return volume;
+	default:
+		return regs[address % sizeof(regs)];
+	}
+}
+
+void sid_write(int address, int data)
+{
+	switch(address & 0x001f)
+	{
+	case 0x0018:
+		volume = data & 0x0f;
+		if(record_buffer != 0)
+			record(total_cycles, (volume << 4) | volume);
+		break;
+	default:
+		regs[address % sizeof(regs)] = data;
+	}
+}
+
-- 
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