AUDIO: Support 96kHz audio rates in ARM assembler rate conversion.

This should be the same changes as fuzzie's previous commit to the C++
version.

1 files changed, 16 insertions, 5 deletions

diff --git a/audio/rate_arm.cpp b/audio/rate_arm.cpp
index 4135cdd1af..371e615efd 100644
--- a/audio/rate_arm.cpp
+++ b/audio/rate_arm.cpp
@@ -68,6 +68,16 @@ namespace Audio {
  */
 #define INTERMEDIATE_BUFFER_SIZE 512
 
+/**
+ * The default fractional type in frac.h (with 16 fractional bits) limits
+ * the rate conversion code to 65536Hz audio: we need to able to handle
+ * 96kHz audio, so we use fewer fractional bits in this code.
+ */
+enum {
+	FRAC_BITS_LOW = 15,
+	FRAC_ONE_LOW = (1L << FRAC_BITS_LOW),
+	FRAC_HALF_LOW = (1L << (FRAC_BITS_LOW-1))
+};
 
 /**
  * Audio rate converter based on simple resampling. Used when no
@@ -287,17 +297,18 @@ LinearRateConverter<stereo, reverseStereo>::LinearRateConverter(st_rate_t inrate
 		error("Input and Output rates must be different to use rate effect");
 	}
 
-	if (inrate >= 65536 || outrate >= 65536) {
-		error("rate effect can only handle rates < 65536");
+	if (inrate >= 131072 || outrate >= 131072) {
+		error("rate effect can only handle rates < 131072");
 	}
 
-	lr.opos = FRAC_ONE;
+	lr.opos = FRAC_ONE_LOW;
 
 	/* increment */
-	incr = (inrate << FRAC_BITS) / outrate;
+	incr = (inrate << FRAC_BITS_LOW) / outrate;
 
 	lr.opos_inc = incr;
 
+	// FIXME: Does 32768 here need changing to 65536 or 0? Compare to rate.cpp code...
 	lr.ilast[0] = lr.ilast[1] = 32768;
 	lr.icur[0] = lr.icur[1] = 0;
 
@@ -438,7 +449,7 @@ public:
  */
 RateConverter *makeRateConverter(st_rate_t inrate, st_rate_t outrate, bool stereo, bool reverseStereo) {
 	if (inrate != outrate) {
-		if ((inrate % outrate) == 0) {
+		if ((inrate % outrate) == 0 && (inrate < 65536)) {
 			if (stereo) {
 				if (reverseStereo)
 					return new SimpleRateConverter<true, true>(inrate, outrate);