From bd82ca80f7f74595d6e5cd73cdf9e5151725e622 Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
Date: Thu, 17 Jun 2010 00:11:54 -0400
Subject: [PATCH] Fixed-point version of frac_div32()
---
libcelt/plc.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/libcelt/plc.c b/libcelt/plc.c
index 4c2593651..763a5b851 100644
--- a/libcelt/plc.c
+++ b/libcelt/plc.c
@@ -4,9 +4,22 @@
#endif
#ifdef FIXED_POINT
-#define frac_div(a,b) ((celt_word32)((32768*65535+32767)*(float)(a)/(b)))
+static celt_word32 frac_div32(celt_word32 a, celt_word32 b)
+{
+ celt_word32 rcp, result, rem;
+ while (b<(1<<30))
+ {
+ a = SHL32(a,1);
+ b = SHL32(b,1);
+ }
+ rcp = PSHR32(celt_rcp(ROUND16(b,16)),2);
+ result = SHL32(MULT16_32_Q15(rcp, a),1);
+ rem = a-MULT32_32_Q31(result, b);
+ result += SHL32(MULT16_32_Q15(rcp, rem),1);
+ return result;
+}
#else
-#define frac_div(a,b) ((float)(a)/(b))
+#define frac_div32(a,b) ((float)(a)/(b))
#endif
@@ -36,7 +49,7 @@ int p
rr += MULT32_32_Q31(lpc[j],ac[i - j]);
rr += SHR32(ac[i + 1],3);
//r = -RC_SCALING*1.*SHL32(rr,3)/(error+1e-15);
- r = -frac_div(SHL32(rr,3), error);
+ r = -frac_div32(SHL32(rr,3), error);
/* Update LPC coefficients and total error */
lpc[i] = SHR32(r,3);
for (j = 0; j < (i+1)>>1; j++)
@@ -49,8 +62,14 @@ int p
}
error = error - MULT32_32_Q31(MULT32_32_Q31(r,r),error);
- if (error<.00001*ac[0])
+ /* Bail out once we get 30 dB gain */
+#ifdef FIXED_POINT
+ if (error<SHR32(ac[0],10))
+ break;
+#else
+ if (error<.001*ac[0])
break;
+#endif
}
}
#ifdef FIXED_POINT
--
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