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Optimizing divisions with a signed numerator

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Jean-Marc Valin 2014-01-30 11:16:24 -05:00
parent 5123175017
commit d9fb8a6651
2 changed files with 15 additions and 2 deletions
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5
celt/bands.c
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@ -630,7 +630,8 @@ static int compute_qn(int N, int b, int offset, int pulse_cap, int stereo)
/* The upper limit ensures that in a stereo split with itheta==16384, we'll /* The upper limit ensures that in a stereo split with itheta==16384, we'll
always have enough bits left over to code at least one pulse in the always have enough bits left over to code at least one pulse in the
side; otherwise it would collapse, since it doesn't get folded. */ side; otherwise it would collapse, since it doesn't get folded. */
qb = IMIN(b-pulse_cap-(4<<BITRES), (b+N2*offset)/N2); qb = celt_sudiv(b+N2*offset, N2);
qb = IMIN(b-pulse_cap-(4<<BITRES), qb);
qb = IMIN(8<<BITRES, qb); qb = IMIN(8<<BITRES, qb);
@ -1434,7 +1435,7 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
ctx.remaining_bits = remaining_bits; ctx.remaining_bits = remaining_bits;
if (i <= codedBands-1) if (i <= codedBands-1)
{ {
curr_balance = balance / IMIN(3, codedBands-i); curr_balance = celt_sudiv(balance, IMIN(3, codedBands-i));
b = IMAX(0, IMIN(16383, IMIN(remaining_bits+1,pulses[i]+curr_balance))); b = IMAX(0, IMIN(16383, IMIN(remaining_bits+1,pulses[i]+curr_balance)));
} else { } else {
b = 0; b = 0;

12
celt/entcode.h
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@ -137,4 +137,16 @@ static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) {
#endif #endif
} }
static OPUS_INLINE opus_int32 celt_sudiv(opus_int32 n, opus_int32 d) {
celt_assert(d>0);
#ifdef USE_SMALL_DIV_TABLE
if (n<0)
return -(opus_int32)celt_udiv(-n, d);
else
return celt_udiv(n, d);
#else
return n/d;
#endif
}
#endif #endif