ref: 3a9699ee9496765c9ffd450e3685044d548c58ab
parent: bd82ca80f7f74595d6e5cd73cdf9e5151725e622
author: Jean-Marc Valin <[email protected]>
date: Wed Jun 16 20:35:26 EDT 2010
minor tweaks to frac_div32()
--- a/libcelt/plc.c
+++ b/libcelt/plc.c
@@ -6,13 +6,14 @@
#ifdef FIXED_POINT
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);
+ celt_word16 rcp;
+ celt_word32 result, rem;
+ int shift = 30-celt_ilog2(b);
+ a = SHL32(a,shift);
+ b = SHL32(b,shift);
+
+ /* 16-bit reciprocal */
+ rcp = ROUND16(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);
@@ -48,7 +49,6 @@
for (j = 0; j < i; j++)
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_div32(SHL32(rr,3), error);
/* Update LPC coefficients and total error */
lpc[i] = SHR32(r,3);