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Adjust fixed-point hermite resampler. Use signed arithmetic.

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This commit is contained in:
Brandon Wright 2012-02-02 15:48:17 -06:00
parent 93cf0a77b9
commit 8db1c467ac
1 changed files with 16 additions and 18 deletions
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34
apu/hermite_resampler.h
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@ -19,27 +19,25 @@ class HermiteResampler : public Resampler
int r_left[4], r_right[4]; int r_left[4], r_right[4];
static inline int32 static inline int32
hermite (uint32 mu1, int32 a, int32 b, int32 c, int32 d) hermite (int32 mu1, int32 a, int32 b, int32 c, int32 d)
{ {
uint32 mu2, mu3, m0, m1, a0, a1, a2, a3; int32 mu2, mu3, m0, m1, a0, a1, a2, a3;
mu2 = (mu1 * mu1) >> 15; mu2 = (mu1 * mu1) >> 15;
mu3 = (mu2 * mu1) >> 15; mu3 = (mu2 * mu1) >> 15;
m0 = (c - a + 32768) << 14; m0 = (c - a) << 14;
m1 = (d - b + 32768) << 14; m1 = (d - b) << 14;
a0 = (mu3 << 1) - (3 * mu2) + (1 << 15); a0 = (mu3 << 1) - (3 * mu2) + (1 << 15);
a1 = mu3 - (mu2 << 1) + mu1; a1 = mu3 - (mu2 << 1) + mu1;
a2 = mu3 - mu2; a2 = mu3 - mu2;
a3 = 3 * mu2 - (mu3 << 1); a3 = 3 * mu2 - (mu3 << 1);
return (int32) (( return (a0 * b) +
(a0 * (b + 32768)) + ((a1 * m0) >> 15) +
((a1 * m0) >> 15) + ((a2 * m1) >> 15) +
((a2 * m1) >> 15) + (a3 * c) >> 15;
(a3 * (c + 32768))
) >> 15) - 32768;
} }
public: public:
@ -55,7 +53,7 @@ class HermiteResampler : public Resampler
void void
time_ratio (double ratio) time_ratio (double ratio)
{ {
r_step = (1 << 15) * ratio; r_step = (1 << 16) * ratio;
clear (); clear ();
} }
@ -63,7 +61,7 @@ class HermiteResampler : public Resampler
clear (void) clear (void)
{ {
ring_buffer::clear (); ring_buffer::clear ();
r_frac = (1 << 15); r_frac = (1 << 16);
r_left [0] = r_left [1] = r_left [2] = r_left [3] = 0; r_left [0] = r_left [1] = r_left [2] = r_left [3] = 0;
r_right[0] = r_right[1] = r_right[2] = r_right[3] = 0; r_right[0] = r_right[1] = r_right[2] = r_right[3] = 0;
} }
@ -83,11 +81,11 @@ class HermiteResampler : public Resampler
int s_right = internal_buffer[i_position + 1]; int s_right = internal_buffer[i_position + 1];
int hermite_val; int hermite_val;
while (r_frac <= (1 << 15) && o_position < num_samples) while (r_frac <= (1 << 16) && o_position < num_samples)
{ {
hermite_val = hermite (r_frac, r_left [0], r_left [1], r_left [2], r_left [3]); hermite_val = hermite (r_frac >> 1, r_left [0], r_left [1], r_left [2], r_left [3]);
data[o_position] = SHORT_CLAMP (hermite_val); data[o_position] = SHORT_CLAMP (hermite_val);
hermite_val = hermite (r_frac, r_right[0], r_right[1], r_right[2], r_right[3]); hermite_val = hermite (r_frac >> 1, r_right[0], r_right[1], r_right[2], r_right[3]);
data[o_position + 1] = SHORT_CLAMP (hermite_val); data[o_position + 1] = SHORT_CLAMP (hermite_val);
o_position += 2; o_position += 2;
@ -95,7 +93,7 @@ class HermiteResampler : public Resampler
r_frac += r_step; r_frac += r_step;
} }
if (r_frac > (1 << 15)) if (r_frac > (1 << 16))
{ {
r_left [0] = r_left [1]; r_left [0] = r_left [1];
r_left [1] = r_left [2]; r_left [1] = r_left [2];
@ -107,7 +105,7 @@ class HermiteResampler : public Resampler
r_right[2] = r_right[3]; r_right[2] = r_right[3];
r_right[3] = s_right; r_right[3] = s_right;
r_frac -= (1 << 15); r_frac -= (1 << 16);
i_position += 2; i_position += 2;
if (i_position >= max_samples) if (i_position >= max_samples)
@ -125,7 +123,7 @@ class HermiteResampler : public Resampler
inline int inline int
avail (void) avail (void)
{ {
return ((((uint32) size) << 13) - r_frac) / r_step * 2; return ((((uint32) size) << 14) - r_frac) / r_step * 2;
} }
}; };