k005289: fix off by 1 error

src/devices/sound/k005289.cpp

@@ -37,10 +37,6 @@
 #include "emu.h"
 #include "k005289.h"
 
-// is this an actual hardware limit? or just an arbitrary divider
-// to bring the output frequency down to a reasonable value for MAME?
-#define CLOCK_DIVIDER 32
-
 // device type definition
 DEFINE_DEVICE_TYPE(K005289, k005289_device, "k005289", "K005289 SCC")
 
@@ -97,7 +93,7 @@ void k005289_device::sound_stream_update(sound_stream &stream, std::vector<read_
 		for (int i = 0; i < 2; i++)
 		{
 			voice_t &v = m_voice[i];
-			if ((v.counter--) < 0)
+			if ((v.counter--) <= 0)
 			{
 				v.waveform = (v.waveform & ~0x1f) | ((v.waveform + 1) & 0x1f);
 				v.counter = v.frequency;