--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cdd_fader.c	Wed Feb 02 01:10:07 2022 -0800
@@ -0,0 +1,65 @@
+#include "cdd_fader.h"
+#include <stdio.h>
+
+void cdd_fader_init(cdd_fader *fader)
+{
+	fader->audio = render_audio_source(16934400, 384, 2);
+	fader->cur_attenuation = 0x4000;
+	fader->dst_attenuation = 0x4000;
+	fader->attenuation_step = 0;
+}
+void cdd_fader_attenuation_write(cdd_fader *fader, uint16_t attenuation)
+{
+	fader->dst_attenuation = attenuation & 0xFFF0;
+	fader->flags = attenuation & 0xE;
+	if (fader->dst_attenuation > fader->cur_attenuation) {
+		fader->attenuation_step = (fader->dst_attenuation - fader->cur_attenuation) >> 4;
+	} else if (fader->dst_attenuation < fader->cur_attenuation) {
+		fader->attenuation_step = (fader->cur_attenuation - fader->dst_attenuation) >> 4;
+	} else {
+		fader->attenuation_step = 0;
+	}
+}
+
+void cdd_fader_data(cdd_fader *fader, uint8_t byte)
+{
+	fader->bytes[fader->byte_counter++] = byte;
+	if (fader->byte_counter == sizeof(fader->bytes)) {
+		fader->byte_counter = 0;
+		int32_t left = (fader->bytes[1] << 8) | fader->bytes[0];
+		int32_t right = (fader->bytes[3] << 8) | fader->bytes[2];
+		if (left & 0x8000) {
+			left |= 0xFFFF0000;
+		}
+		if (right & 0x8000) {
+			right |= 0xFFFF0000;
+		}
+		if (!fader->cur_attenuation) {
+			left = right = 0;
+		} else if (fader->cur_attenuation >= 4) {
+			left *= fader->cur_attenuation & 0x7FF0;
+			right *= fader->cur_attenuation & 0x7FF0;
+			left >>= 14;
+			right >>= 14;
+		} else {
+			//TODO: FIXME
+			left = right = 0;
+		}
+		render_put_stereo_sample(fader->audio, left, right);
+		if (fader->attenuation_step) {
+			if (fader->dst_attenuation > fader->cur_attenuation) {
+				fader->cur_attenuation += fader->attenuation_step;
+				if (fader->cur_attenuation >= fader->dst_attenuation) {
+					fader->cur_attenuation = fader->dst_attenuation;
+					fader->attenuation_step = 0;
+				}
+			} else {
+				fader->cur_attenuation -= fader->attenuation_step;
+				if (fader->cur_attenuation <= fader->dst_attenuation) {
+					fader->cur_attenuation = fader->dst_attenuation;
+					fader->attenuation_step = 0;
+				}
+			}
+		}
+	}
+}