utility to reset OPL chips from dos

LICENSE

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+Copyright (c) 2021 Michael Gernoth <[email protected]>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to
+deal in the Software without restriction, including without limitation the
+rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE.

README.md

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+# Reset OPL2/3
+
+This utility resets an OPL2/3 chip (including stopping all playing notes).
+
+Without an argument, it assumes 0x220 as the base address:
+
+```
+C:\> resetopl
+No argument given, assuming base at 0x220
+Resetting OPL3 at 0x220
+```
+
+You can override the base by providing it as an argument:
+```
+C:\> resetopl 0x240
+Resetting OPL3 at 0x240
+```
+
+The utility detects if the OPL-chip is present and will abort if the chip
+is not detected:
+```
+C:\> resetopl 0x230
+OPL not detected at 0x230
+```
+
+This tool is compiled with Turbo C 2.01.
+
+Download a compiled version from "Releases".

resetopl.c

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+/* OPL2/3 reset
+ *
+ * Copyright (c) 2021 Michael Gernoth <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <io.h>
+
+void write_opl(unsigned int base, int opl3, unsigned char reg, unsigned char v) {
+	unsigned int oplbase = base;
+
+	if (opl3) {
+		oplbase += 2;
+	}
+	outportb(oplbase, reg);
+	inportb(base);
+	outportb(oplbase+1, v);
+	inportb(base);
+}
+
+void set_registers(unsigned int base, unsigned char low, unsigned char high, unsigned char val, int opl3) {
+	unsigned char reg;
+
+	for (reg = low; reg <= high; reg++) {
+		write_opl(base, 0, reg, val);
+		if (opl3) {
+			write_opl(base, 1, reg, val);
+		}
+	}
+}
+
+int main(int argc, char **argv) {
+	unsigned int base;
+	unsigned char val1, val2;
+	int opl3 = 0;
+
+	if (argc == 1) {
+		base = 0x220;
+		printf("No argument given, assuming base at 0x%x\n", base);
+	} else if (argc == 2) {
+		char *endp;
+		base = strtoul(argv[1], &endp, 0);
+		if (*endp != '\0') {
+			fprintf(stderr, "Invalid base address %s!\n", argv[1]);
+			exit(1);
+		}
+	}
+
+	if (!base) {
+		fprintf(stderr, "Syntax: %s base-addr\n", argv[0]);
+		exit(1);
+	}
+
+	/* Detect chip */
+	/* Reset timer 1 and 2 */
+	write_opl(base, 0, 0x4, 0x60);
+
+	/* Reset IRQ */
+	write_opl(base, 0, 0x4, 0x80);
+
+	/* Read status */
+	val1 = inportb(base);
+
+	/* Set timer 1 to 0xff */
+	write_opl(base, 0, 0x2, 0xff);
+
+	/* Start timer 1 */
+	write_opl(base, 0, 0x4, 0x21);
+
+	/* Delay for more than 80us, pick 10ms */
+	delay(10);
+
+	/* Read status */
+	val2 = inportb(base);
+
+	/* Reset timer 1 and 2 */
+	write_opl(base, 0, 0x4, 0x60);
+
+	/* Reset IRQ */
+	write_opl(base, 0, 0x4, 0x80);
+
+	if ((val1&0xe0) != 0x00 || (val2&0xe0) != 0xc0) {
+		fprintf(stderr, "OPL not detected at 0x%x\n", base);
+		exit(1);
+	}
+	/* Read status */
+	val1 = inportb(base);
+
+	if ((val1 & 0x06) == 0x00) {
+		opl3 = 1;
+	}
+
+	printf("Resetting OPL%d at 0x%x...\n", 2+opl3, base);
+
+	/* Tremolo/Vibrato */
+	set_registers(base, 0x20, 0x35, 0, opl3);
+
+	/* Frequency number */
+	set_registers(base, 0xa0, 0xa8, 0, opl3);
+
+	/* Key off */
+	set_registers(base, 0xb0, 0xb8, 0, opl3);
+
+	/* Drum off */
+	set_registers(base, 0xbd, 0xbd, 0, opl3);
+
+	/* Feedback */
+	set_registers(base, 0xc0, 0xc8, 0, opl3);
+
+	/* Waveform */
+	set_registers(base, 0xe0, 0xf5, 0, opl3);
+
+	/* CSW/Note SEL */
+	set_registers(base, 0x08, 0x08, 0, opl3);
+
+	/* Test/Waveform select */
+	set_registers(base, 0x01, 0x01, 0, opl3);
+
+	/* OPL2 */
+	write_opl(base, 1, 4, 0);
+	write_opl(base, 1, 5, 0);
+
+	return 0;
+}