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.

2 files changed, 33 insertions, 22 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);
diff --git a/audio/rate_arm_asm.s b/audio/rate_arm_asm.s
index ac999f66e4..87e4c8aaf9 100644
--- a/audio/rate_arm_asm.s
+++ b/audio/rate_arm_asm.s
@@ -434,17 +434,17 @@ LinearRate_M_part2:
 
         LDRSH   r4, [r3]                @ r4 = obuf[0]
         LDRSH   r5, [r3,#2]             @ r5 = obuf[1]
-        MOV     r6, r6, ASR #16         @ r6 = tmp0 = tmp1 >>= 16
+        MOV     r6, r6, ASR #15         @ r6 = tmp0 = tmp1 >>= 15
         MUL     r7, r12,r6              @ r7 = tmp0*vol_l
         MUL     r6, r14,r6              @ r6 = tmp1*vol_r
 
-        ADDS    r7, r7, r4, LSL #16     @ r7 = obuf[0]<<16 + tmp0*vol_l
+        ADDS    r7, r7, r4, LSL #15     @ r7 = obuf[0]<<15 + tmp0*vol_l
         RSCVS   r7, r10, #0x80000000    @ Clamp r7
-        ADDS    r6, r6, r5, LSL #16     @ r6 = obuf[1]<<16 + tmp1*vol_r
+        ADDS    r6, r6, r5, LSL #15     @ r6 = obuf[1]<<15 + tmp1*vol_r
         RSCVS   r6, r10, #0x80000000    @ Clamp r6
 
-        MOV     r7, r7, LSR #16         @ Shift back to halfword
-        MOV     r6, r6, LSR #16         @ Shift back to halfword
+        MOV     r7, r7, LSR #15         @ Shift back to halfword
+        MOV     r6, r6, LSR #15         @ Shift back to halfword
 
         LDR     r5, [r2,#12]            @ r5 = opos_inc
         STRH    r7, [r3],#2             @ Store output value
@@ -530,23 +530,23 @@ LinearRate_S_part2:
         LDR     r7, [r2,#24]            @ r7 = ilast[1]<<16 + 32768
         LDRSH   r5, [r2,#18]            @ r5 = icur[1]
         LDRSH   r10,[r3]                @ r10= obuf[0]
-        MOV     r6, r6, ASR #16         @ r6 = tmp1 >>= 16
+        MOV     r6, r6, ASR #15         @ r6 = tmp1 >>= 15
         SUB     r5, r5, r7, ASR #16     @ r5 = icur[1] - ilast[1]
         MLA     r7, r4, r5, r7  @ r7 = (icur[1]-ilast[1])*opos_frac+ilast[1]
 
         LDRSH   r5, [r3,#2]             @ r5 = obuf[1]
-        MOV     r7, r7, ASR #16         @ r7 = tmp0 >>= 16
+        MOV     r7, r7, ASR #15         @ r7 = tmp0 >>= 15
         MUL     r7, r12,r7              @ r7 = tmp0*vol_l
         MUL     r6, r14,r6              @ r6 = tmp1*vol_r
 
-        ADDS    r7, r7, r10, LSL #16    @ r7 = obuf[0]<<16 + tmp0*vol_l
+        ADDS    r7, r7, r10, LSL #15    @ r7 = obuf[0]<<15 + tmp0*vol_l
         MOV     r4, #0
         RSCVS   r7, r4, #0x80000000     @ Clamp r7
-        ADDS    r6, r6, r5, LSL #16     @ r6 = obuf[1]<<16 + tmp1*vol_r
+        ADDS    r6, r6, r5, LSL #15     @ r6 = obuf[1]<<15 + tmp1*vol_r
         RSCVS   r6, r4, #0x80000000     @ Clamp r6
 
-        MOV     r7, r7, LSR #16         @ Shift back to halfword
-        MOV     r6, r6, LSR #16         @ Shift back to halfword
+        MOV     r7, r7, LSR #15         @ Shift back to halfword
+        MOV     r6, r6, LSR #15         @ Shift back to halfword
 
         LDR     r5, [r2,#12]            @ r5 = opos_inc
         STRH    r7, [r3],#2             @ Store output value
@@ -632,23 +632,23 @@ LinearRate_R_part2:
         LDR     r7, [r2,#24]            @ r7 = ilast[1]<<16 + 32768
         LDRSH   r5, [r2,#18]            @ r5 = icur[1]
         LDRSH   r10,[r3,#2]             @ r10= obuf[1]
-        MOV     r6, r6, ASR #16         @ r6 = tmp1 >>= 16
+        MOV     r6, r6, ASR #15         @ r6 = tmp1 >>= 15
         SUB     r5, r5, r7, ASR #16     @ r5 = icur[1] - ilast[1]
         MLA     r7, r4, r5, r7  @ r7 = (icur[1]-ilast[1])*opos_frac+ilast[1]
 
         LDRSH   r5, [r3]                @ r5 = obuf[0]
-        MOV     r7, r7, ASR #16         @ r7 = tmp0 >>= 16
+        MOV     r7, r7, ASR #15         @ r7 = tmp0 >>= 15
         MUL     r7, r12,r7              @ r7 = tmp0*vol_l
         MUL     r6, r14,r6              @ r6 = tmp1*vol_r
 
-        ADDS    r7, r7, r10, LSL #16    @ r7 = obuf[1]<<16 + tmp0*vol_l
+        ADDS    r7, r7, r10, LSL #15    @ r7 = obuf[1]<<15 + tmp0*vol_l
         MOV     r4, #0
         RSCVS   r7, r4, #0x80000000     @ Clamp r7
-        ADDS    r6, r6, r5, LSL #16     @ r6 = obuf[0]<<16 + tmp1*vol_r
+        ADDS    r6, r6, r5, LSL #15     @ r6 = obuf[0]<<15 + tmp1*vol_r
         RSCVS   r6, r4, #0x80000000     @ Clamp r6
 
-        MOV     r7, r7, LSR #16         @ Shift back to halfword
-        MOV     r6, r6, LSR #16         @ Shift back to halfword
+        MOV     r7, r7, LSR #15         @ Shift back to halfword
+        MOV     r6, r6, LSR #15         @ Shift back to halfword
 
         LDR     r5, [r2,#12]            @ r5 = opos_inc
         STRH    r6, [r3],#2             @ Store output value