frequency sweep

Author: jotego

sgdk/freq_sweep/test.c

@@ -0,0 +1,49 @@
+#include <genesis.h>
+#include <ym2612.h>
+
+void write_freq( int freq ) {
+    char aux = freq>>8;
+    YM2612_writeReg( 0, 0xa4, aux );
+    aux = freq&0xff;
+    YM2612_writeReg( 0, 0xa4, aux );
+}
+
+int main() {
+    char ymregs[] = {
+        0xb0, 0x07, // FB - connect
+        0xb4, 0xc0, // LR
+        0x30, 0x01, // DT - MULT
+        0x40, 0x00, // TL
+        0x50, 0x1f, // AR
+        0x60, 0x00, // DR
+        0x70, 0x00, // SR
+
+        0x80, 0x00, // SL+RR
+        0x90, 0x00, // SSG
+        0xa4, 0x00, // Block
+        0xa0, 0x00  // Fnum
+    };
+    int k;
+    int ssg=7;
+    int inc=1;
+    Z80_requestBus(1000);
+    // YM2612_reset();
+    for ( k=0; k<sizeof(ymregs); k+=2 ) {
+        YM2612_writeReg( 0, ymregs[k], ymregs[k+1]);
+    }
+    VDP_drawText("Freq sweep", 10, 13);
+    YM2612_writeReg( 0, 0x28, 0x10 ); // key-on channel 0 op 0
+    while(1) {
+        unsigned k1;
+        int freq=0;
+        for(k1=160;k1>0;k1--) {
+            unsigned k2=0xffff;
+            while(k2--);
+        }
+        if(freq==0) inc=1;
+        freq+=inc;
+        if(freq>0xc000) inc=-1;
+        YM2612_writeReg( freq );
+    }
+    return 0;
+}

sgdk/freq_sweep/test.cbp

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+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<CodeBlocks_project_file>
+	<FileVersion major="1" minor="6" />
+	<Project>
+		<Option title="test" />
+		<Option makefile="c:/sgdk/makefile.gen" />
+		<Option makefile_is_custom="1" />
+		<Option pch_mode="2" />
+		<Option compiler="sega_genesis_compiler" />
+		<Build>
+			<Target title="default">
+				<Option output="out/test" prefix_auto="1" extension_auto="1" />
+				<Option object_output="out/" />
+				<Option type="1" />
+				<Option compiler="sega_genesis_compiler" />
+				<Compiler>
+					<Add option="-O2" />
+				</Compiler>
+				<Linker>
+					<Add option="-s" />
+				</Linker>
+			</Target>
+		</Build>
+		<Compiler>
+			<Add option="-Wall" />
+		</Compiler>
+		<Unit filename="test.c">
+			<Option compilerVar="CC" />
+		</Unit>
+		<Extensions>
+			<code_completion />
+			<envvars />
+			<debugger />
+		</Extensions>
+	</Project>
+</CodeBlocks_project_file>

sgdk/freq_sweep/test.layout

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+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<CodeBlocks_layout_file>
+	<FileVersion major="1" minor="0" />
+	<ActiveTarget name="default" />
+	<File name="test.c" open="1" top="1" tabpos="1" split="0" active="1" splitpos="0" zoom_1="0" zoom_2="0">
+		<Cursor>
+			<Cursor1 position="632" topLine="0" />
+		</Cursor>
+	</File>
+</CodeBlocks_layout_file>