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authorThom Johansen <thomj@rockbox.org>2007-02-05 01:01:15 +0000
committerThom Johansen <thomj@rockbox.org>2007-02-05 01:01:15 +0000
commit5f48e1590f16049aaaf916ad72d6016a4e7ffa5c (patch)
tree4438397a1a44cf301f0f4675388f92ee1e8ddb38 /apps
parent7170a00daad917993d3fed460f1122f543d2b0ea (diff)
downloadrockbox-5f48e1590f16049aaaf916ad72d6016a4e7ffa5c.tar.gz
rockbox-5f48e1590f16049aaaf916ad72d6016a4e7ffa5c.zip
Optimise EQ coef calculation routines for both speed and size. Move now unneeded fsqrt function to plugin fixed point library in case it'll be needed. Move all fixed point helper macros to dsp.h. Added FRACMUL_SHL macro to facilitate high-precision shifting of 64 bit multiplies and remove rounding from macsr in main thread to make this work as intended.
Tested quite thorougly, but as always, be careful with your ears. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12203 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps')
-rw-r--r--apps/dsp.c121
-rw-r--r--apps/dsp.h159
-rw-r--r--apps/eq.c183
-rw-r--r--apps/plugins/lib/fixedpoint.c19
-rw-r--r--apps/plugins/lib/fixedpoint.h2
5 files changed, 251 insertions, 233 deletions
diff --git a/apps/dsp.c b/apps/dsp.c
index 81a1d29e11..c4630ada77 100644
--- a/apps/dsp.c
+++ b/apps/dsp.c
@@ -44,123 +44,6 @@
#define RESAMPLE_BUF_SIZE (256 * 4) /* Enough for 11,025 Hz -> 44,100 Hz*/
#define DEFAULT_GAIN 0x01000000
-#if defined(CPU_COLDFIRE) && !defined(SIMULATOR)
-
-/* Multiply two S.31 fractional integers and return the sign bit and the
- * 31 most significant bits of the result.
- */
-#define FRACMUL(x, y) \
-({ \
- long t; \
- asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
- "movclr.l %%acc0, %[t]\n\t" \
- : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
- t; \
-})
-
-/* Multiply one S.31-bit and one S8.23 fractional integer and return the
- * sign bit and the 31 most significant bits of the result.
- */
-#define FRACMUL_8(x, y) \
-({ \
- long t; \
- long u; \
- asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
- "move.l %%accext01, %[u]\n\t" \
- "movclr.l %%acc0, %[t]\n\t" \
- : [t] "=r" (t), [u] "=r" (u) : [a] "r" (x), [b] "r" (y)); \
- (t << 8) | (u & 0xff); \
-})
-
-/* Multiply one S.31-bit and one S8.23 fractional integer and return the
- * sign bit and the 31 most significant bits of the result. Load next value
- * to multiply with into x from s (and increase s); x must contain the
- * initial value.
- */
-#define FRACMUL_8_LOOP_PART(x, s, d, y) \
-{ \
- long u; \
- asm volatile ("mac.l %[a], %[b], (%[c])+, %[a], %%acc0\n\t" \
- "move.l %%accext01, %[u]\n\t" \
- "movclr.l %%acc0, %[t]" \
- : [a] "+r" (x), [c] "+a" (s), [t] "=r" (d), [u] "=r" (u) \
- : [b] "r" (y)); \
- d = (d << 8) | (u & 0xff); \
-}
-
-#define FRACMUL_8_LOOP(x, y, s, d) \
-{ \
- long t; \
- FRACMUL_8_LOOP_PART(x, s, t, y); \
- asm volatile ("move.l %[t],(%[d])+" \
- : [d] "+a" (d)\
- : [t] "r" (t)); \
-}
-
-#define ACC(acc, x, y) \
- (void)acc; \
- asm volatile ("mac.l %[a], %[b], %%acc0" \
- : : [a] "i,r" (x), [b] "i,r" (y));
-#define GET_ACC(acc) \
-({ \
- long t; \
- (void)acc; \
- asm volatile ("movclr.l %%acc0, %[t]" \
- : [t] "=r" (t)); \
- t; \
-})
-
-#define ACC_INIT(acc, x, y) ACC(acc, x, y)
-
-#elif defined(CPU_ARM) && !defined(SIMULATOR)
-
-/* Multiply two S.31 fractional integers and return the sign bit and the
- * 31 most significant bits of the result.
- */
-#define FRACMUL(x, y) \
-({ \
- long t; \
- asm volatile ("smull r0, r1, %[a], %[b]\n\t" \
- "mov %[t], r1, asl #1\n\t" \
- "orr %[t], %[t], r0, lsr #31\n\t" \
- : [t] "=r" (t) : [a] "r" (x), [b] "r" (y) : "r0", "r1"); \
- t; \
-})
-
-#define ACC_INIT(acc, x, y) acc = FRACMUL(x, y)
-#define ACC(acc, x, y) acc += FRACMUL(x, y)
-#define GET_ACC(acc) acc
-
-/* Multiply one S.31-bit and one S8.23 fractional integer and store the
- * sign bit and the 31 most significant bits of the result to d (and
- * increase d). Load next value to multiply with into x from s (and
- * increase s); x must contain the initial value.
- */
-#define FRACMUL_8_LOOP(x, y, s, d) \
-({ \
- asm volatile ("smull r0, r1, %[a], %[b]\n\t" \
- "mov %[t], r1, asl #9\n\t" \
- "orr %[t], %[t], r0, lsr #23\n\t" \
- : [t] "=r" (*(d)++) : [a] "r" (x), [b] "r" (y) : "r0", "r1"); \
- x = *(s)++; \
-})
-
-#else
-
-#define ACC_INIT(acc, x, y) acc = FRACMUL(x, y)
-#define ACC(acc, x, y) acc += FRACMUL(x, y)
-#define GET_ACC(acc) acc
-#define FRACMUL(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 31))
-#define FRACMUL_8(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 23))
-#define FRACMUL_8_LOOP(x, y, s, d) \
-({ \
- long t = x; \
- x = *(s)++; \
- *(d)++ = (long) (((((long long) (t)) * ((long long) (y))) >> 23)); \
-})
-
-#endif
-
struct dsp_config
{
long codec_frequency; /* Sample rate of data coming from the codec */
@@ -671,8 +554,8 @@ void dsp_set_eq_coefs(int band)
/* Convert user settings to format required by coef generator functions */
cutoff = 0xffffffff / NATIVE_FREQUENCY * (*setting++);
- q = ((*setting++) << 16) / 10; /* 16.16 */
- gain = ((*setting++) << 16) / 10; /* s15.16 */
+ q = *setting++;
+ gain = *setting++;
if (q == 0)
q = 1;
diff --git a/apps/dsp.h b/apps/dsp.h
index 1a2b8782f3..ccea8cba34 100644
--- a/apps/dsp.h
+++ b/apps/dsp.h
@@ -47,6 +47,165 @@ enum {
DSP_CROSSFEED
};
+/* A bunch of fixed point assembler helper macros */
+#if defined(CPU_COLDFIRE) && !defined(SIMULATOR)
+
+/* Multiply two S.31 fractional integers and return the sign bit and the
+ * 31 most significant bits of the result.
+ */
+#define FRACMUL(x, y) \
+({ \
+ long t; \
+ asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
+ "movclr.l %%acc0, %[t]\n\t" \
+ : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
+ t; \
+})
+
+/* Multiply two S.31 fractional integers, and return the 32 most significant
+ * bits after a shift left by the constant z. NOTE: Only works for shifts of
+ * up to 8 on Coldfire!
+ */
+#define FRACMUL_SHL(x, y, z) \
+({ \
+ long t, t2; \
+ asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
+ "moveq.l %[d], %[t]\n\t" \
+ "move.l %%accext01, %[t2]\n\t" \
+ "and.l %[mask], %[t2]\n\t" \
+ "lsr.l %[t], %[t2]\n\t" \
+ "movclr.l %%acc0, %[t]\n\t" \
+ "asl.l %[c], %[t]\n\t" \
+ "or.l %[t2], %[t]\n\t" \
+ : [t] "=d" (t), [t2] "=d" (t2) \
+ : [a] "r" (x), [b] "r" (y), [mask] "d" (0xff), \
+ [c] "i" ((z)), [d] "i" (8 - (z))); \
+ t; \
+})
+
+/* Multiply one S.31-bit and one S8.23 fractional integer and return the
+ * sign bit and the 31 most significant bits of the result.
+ */
+#define FRACMUL_8(x, y) \
+({ \
+ long t; \
+ long u; \
+ asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
+ "move.l %%accext01, %[u]\n\t" \
+ "movclr.l %%acc0, %[t]\n\t" \
+ : [t] "=r" (t), [u] "=r" (u) : [a] "r" (x), [b] "r" (y)); \
+ (t << 8) | (u & 0xff); \
+})
+
+/* Multiply one S.31-bit and one S8.23 fractional integer and return the
+ * sign bit and the 31 most significant bits of the result. Load next value
+ * to multiply with into x from s (and increase s); x must contain the
+ * initial value.
+ */
+#define FRACMUL_8_LOOP_PART(x, s, d, y) \
+{ \
+ long u; \
+ asm volatile ("mac.l %[a], %[b], (%[c])+, %[a], %%acc0\n\t" \
+ "move.l %%accext01, %[u]\n\t" \
+ "movclr.l %%acc0, %[t]" \
+ : [a] "+r" (x), [c] "+a" (s), [t] "=r" (d), [u] "=r" (u) \
+ : [b] "r" (y)); \
+ d = (d << 8) | (u & 0xff); \
+}
+
+#define FRACMUL_8_LOOP(x, y, s, d) \
+{ \
+ long t; \
+ FRACMUL_8_LOOP_PART(x, s, t, y); \
+ asm volatile ("move.l %[t],(%[d])+" \
+ : [d] "+a" (d)\
+ : [t] "r" (t)); \
+}
+
+#define ACC(acc, x, y) \
+ (void)acc; \
+ asm volatile ("mac.l %[a], %[b], %%acc0" \
+ : : [a] "i,r" (x), [b] "i,r" (y));
+
+#define GET_ACC(acc) \
+({ \
+ long t; \
+ (void)acc; \
+ asm volatile ("movclr.l %%acc0, %[t]" \
+ : [t] "=r" (t)); \
+ t; \
+})
+
+#define ACC_INIT(acc, x, y) ACC(acc, x, y)
+
+#elif defined(CPU_ARM) && !defined(SIMULATOR)
+
+/* Multiply two S.31 fractional integers and return the sign bit and the
+ * 31 most significant bits of the result.
+ */
+#define FRACMUL(x, y) \
+({ \
+ long t; \
+ asm volatile ("smull r0, r1, %[a], %[b]\n\t" \
+ "mov %[t], r1, asl #1\n\t" \
+ "orr %[t], %[t], r0, lsr #31\n\t" \
+ : [t] "=r" (t) : [a] "r" (x), [b] "r" (y) : "r0", "r1"); \
+ t; \
+})
+
+/* Multiply two S.31 fractional integers, and return the 32 most significant
+ * bits after a shift left by the constant z.
+ */
+#define FRACMUL_SHL(x, y, z) \
+({ \
+ long t; \
+ asm volatile ("smull r0, r1, %[a], %[b]\n\t" \
+ "mov %[t], r1, asl %[c]\n\t" \
+ "orr %[t], %[t], r0, lsr %[d]\n\t" \
+ : [t] "=r" (t) \
+ : [a] "r" (x), [b] "r" (y), \
+ [c] "M" ((z) + 1), [d] "M" (31 - (z)) \
+ : "r0", "r1"); \
+ t; \
+})
+
+#define ACC_INIT(acc, x, y) acc = FRACMUL(x, y)
+#define ACC(acc, x, y) acc += FRACMUL(x, y)
+#define GET_ACC(acc) acc
+
+/* Multiply one S.31-bit and one S8.23 fractional integer and store the
+ * sign bit and the 31 most significant bits of the result to d (and
+ * increase d). Load next value to multiply with into x from s (and
+ * increase s); x must contain the initial value.
+ */
+#define FRACMUL_8_LOOP(x, y, s, d) \
+({ \
+ asm volatile ("smull r0, r1, %[a], %[b]\n\t" \
+ "mov %[t], r1, asl #9\n\t" \
+ "orr %[t], %[t], r0, lsr #23\n\t" \
+ : [t] "=r" (*(d)++) : [a] "r" (x), [b] "r" (y) : "r0", "r1"); \
+ x = *(s)++; \
+})
+
+#else
+
+#define ACC_INIT(acc, x, y) acc = FRACMUL(x, y)
+#define ACC(acc, x, y) acc += FRACMUL(x, y)
+#define GET_ACC(acc) acc
+#define FRACMUL(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 31))
+#define FRACMUL_SHL(x, y, z) ((long)(((((long long) (x)) * ((long long) (y))) >> (31 - (z)))))
+#define FRACMUL_8(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 23))
+#define FRACMUL_8_LOOP(x, y, s, d) \
+({ \
+ long t = x; \
+ x = *(s)++; \
+ *(d)++ = (long) (((((long long) (t)) * ((long long) (y))) >> 23)); \
+})
+
+#endif
+
+#define DIV64(x, y, z) (long)(((long long)(x) << (z))/(y))
+
long dsp_process(char *dest, const char *src[], long size);
long dsp_input_size(long size);
long dsp_output_size(long size);
diff --git a/apps/eq.c b/apps/eq.c
index bf562c73f2..588c23f89f 100644
--- a/apps/eq.c
+++ b/apps/eq.c
@@ -19,39 +19,9 @@
#include <inttypes.h>
#include "config.h"
+#include "dsp.h"
#include "eq.h"
-
-/* Coef calculation taken from Audio-EQ-Cookbook.txt by Robert Bristow-Johnson.
- Slightly faster calculation can be done by deriving forms which use tan()
- instead of cos() and sin(), but the latter are far easier to use when doing
- fixed point math, and performance is not a big point in the calculation part.
- All the 'a' filter coefficients are negated so we can use only additions
- in the filtering equation.
- We realise the filters as a second order direct form 1 structure. Direct
- form 1 was chosen because of better numerical properties for fixed point
- implementations.
- */
-
-#define DIV64(x, y, z) (long)(((long long)(x) << (z))/(y))
-/* This macro requires the EMAC unit to be in fractional mode
- when the coef generator routines are called. If this can't be guaranteed,
- then add "&& 0" below. This will use a slower coef calculation on Coldfire.
- */
-#if defined(CPU_COLDFIRE) && !defined(SIMULATOR)
-#define FRACMUL(x, y) \
-({ \
- long t; \
- asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
- "movclr.l %%acc0, %[t]\n\t" \
- : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
- t; \
-})
-#else
-#define FRACMUL(x, y) ((long)(((((long long) (x)) * ((long long) (y))) >> 31)))
-#endif
-
-/* TODO: replaygain.c has some fixed point routines. perhaps we could reuse
- them? */
+#include "replaygain.h"
/* Inverse gain of circular cordic rotation in s0.31 format. */
static const long cordic_circular_gain = 0xb2458939; /* 0.607252929 */
@@ -148,46 +118,8 @@ static long fsincos(unsigned long phase, long *cos) {
return y;
}
-/* Fixed point square root via Newton-Raphson.
- * Output is in same fixed point format as input.
- * fracbits specifies number of fractional bits in argument.
- */
-static long fsqrt(long a, unsigned int fracbits)
-{
- long b = a/2 + (1 << fracbits); /* initial approximation */
- unsigned n;
- const unsigned iterations = 4;
-
- for (n = 0; n < iterations; ++n)
- b = (b + DIV64(a, b, fracbits))/2;
-
- return b;
-}
-
-static const short dbtoatab[49] = {
- 2058, 2180, 2309, 2446, 2591, 2744, 2907, 3079, 3261, 3455, 3659, 3876,
- 4106, 4349, 4607, 4880, 5169, 5475, 5799, 6143, 6507, 6893, 7301, 7734,
- 8192, 8677, 9192, 9736, 10313, 10924, 11572, 12257, 12983, 13753, 14568,
- 15431, 16345, 17314, 18340, 19426, 20577, 21797, 23088, 24456, 25905, 27440,
- 29066, 30789, 32613
-};
-
-/* Function for converting dB to squared amplitude factor (A = 10^(dB/40)).
- Range is -24 to 24 dB. If gain values outside of this is needed, the above
- table needs to be extended.
- Parameter format is s15.16 fixed point. Return format is s2.29 fixed point.
- */
-static long dbtoA(long db)
-{
- const unsigned long bias = 24 << 16;
- unsigned short frac = (db + bias) & 0x0000ffff;
- unsigned short pos = (db + bias) >> 16;
- short diff = dbtoatab[pos + 1] - dbtoatab[pos];
-
- return (dbtoatab[pos] << 16) + frac*diff;
-}
-
-/* Calculate first order shelving filter coefficients.
+/**
+ * Calculate first order shelving filter coefficients.
* Note that the filter is not compatible with the eq_filter routine.
* @param cutoff a value from 0 to 0x80000000, where 0 represents 0 Hz and
* 0x80000000 represents the Nyquist frequency (samplerate/2).
@@ -205,8 +137,8 @@ void filter_bishelf_coefs(unsigned long cutoff, long ad, long an, int32_t *c)
cs = one + (cs >> 4);
/* For max A = 4 (24 dB) */
- b0 = (FRACMUL(an, cs) << 4) + (FRACMUL(ad, s) << 4);
- b1 = (FRACMUL(ad, s) << 4) - (FRACMUL(an, cs) << 4);
+ b0 = FRACMUL_SHL(an, cs, 4) + FRACMUL_SHL(ad, s, 4);
+ b1 = FRACMUL_SHL(ad, s, 4) - FRACMUL_SHL(an, cs, 4);
a0 = s + cs;
a1 = s - cs;
@@ -215,36 +147,48 @@ void filter_bishelf_coefs(unsigned long cutoff, long ad, long an, int32_t *c)
c[2] = -DIV64(a1, a0, 31);
}
+/* Coef calculation taken from Audio-EQ-Cookbook.txt by Robert Bristow-Johnson.
+ * Slightly faster calculation can be done by deriving forms which use tan()
+ * instead of cos() and sin(), but the latter are far easier to use when doing
+ * fixed point math, and performance is not a big point in the calculation part.
+ * All the 'a' filter coefficients are negated so we can use only additions
+ * in the filtering equation.
+ */
+
/**
* Calculate second order section peaking filter coefficients.
* @param cutoff a value from 0 to 0x80000000, where 0 represents 0 Hz and
* 0x80000000 represents the Nyquist frequency (samplerate/2).
- * @param Q 16.16 fixed point value describing Q factor. Lower bound
- * is artificially set at 0.5.
- * @param db s15.16 fixed point value describing gain/attenuation at peak freq.
+ * @param Q Q factor value multiplied by ten. Lower bound is artificially set
+ * at 0.5.
+ * @param db decibel value multiplied by ten, describing gain/attenuation at
+ * peak freq.
* @param c pointer to coefficient storage. Coefficients are s3.28 format.
*/
void eq_pk_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
{
- long cc;
+ long cs;
const long one = 1 << 28; /* s3.28 */
- const long A = dbtoA(db);
- const long alpha = DIV64(fsincos(cutoff, &cc), 2*Q, 15); /* s1.30 */
+ const long A = get_replaygain_int(db*5) << 5; /* 10^(db/40), s2.29 */
+ const long alpha = fsincos(cutoff, &cs)/(2*Q)*10 >> 1; /* s1.30 */
int32_t a0, a1, a2; /* these are all s3.28 format */
int32_t b0, b1, b2;
+ const long alphadivA = DIV64(alpha, A, 27);
/* possible numerical ranges are in comments by each coef */
b0 = one + FRACMUL(alpha, A); /* [1 .. 5] */
- b1 = a1 = -2*(cc >> 3); /* [-2 .. 2] */
+ b1 = a1 = -2*(cs >> 3); /* [-2 .. 2] */
b2 = one - FRACMUL(alpha, A); /* [-3 .. 1] */
- a0 = one + DIV64(alpha, A, 27); /* [1 .. 5] */
- a2 = one - DIV64(alpha, A, 27); /* [-3 .. 1] */
-
- c[0] = DIV64(b0, a0, 28); /* [0.25 .. 4] */
- c[1] = DIV64(b1, a0, 28); /* [-2 .. 2] */
- c[2] = DIV64(b2, a0, 28); /* [-2.4 .. 1] */
- c[3] = DIV64(-a1, a0, 28); /* [-2 .. 2] */
- c[4] = DIV64(-a2, a0, 28); /* [-0.6 .. 1] */
+ a0 = one + alphadivA; /* [1 .. 5] */
+ a2 = one - alphadivA; /* [-3 .. 1] */
+
+ /* range of this is roughly [0.2 .. 1], but we'll never hit 1 completely */
+ const long rcp_a0 = DIV64(1, a0, 59); /* s0.31 */
+ *c++ = FRACMUL(b0, rcp_a0); /* [0.25 .. 4] */
+ *c++ = FRACMUL(b1, rcp_a0); /* [-2 .. 2] */
+ *c++ = FRACMUL(b2, rcp_a0); /* [-2.4 .. 1] */
+ *c++ = FRACMUL(-a1, rcp_a0); /* [-2 .. 2] */
+ *c++ = FRACMUL(-a2, rcp_a0); /* [-0.6 .. 1] */
}
/**
@@ -255,20 +199,21 @@ void eq_ls_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
{
long cs;
const long one = 1 << 25; /* s6.25 */
- const long A = dbtoA(db);
- const long alpha = DIV64(fsincos(cutoff, &cs), 2*Q, 15); /* s1.30 */
+ const long sqrtA = get_replaygain_int(db*5/2) << 2; /* 10^(db/80), s5.26 */
+ const long A = FRACMUL_SHL(sqrtA, sqrtA, 8); /* s2.29 */
+ const long alpha = fsincos(cutoff, &cs)/(2*Q)*10 >> 1; /* s1.30 */
const long ap1 = (A >> 4) + one;
const long am1 = (A >> 4) - one;
- const long twosqrtalpha = 2*FRACMUL(fsqrt(A >> 3, 26), alpha);
+ const long twosqrtalpha = 2*FRACMUL(sqrtA, alpha);
int32_t a0, a1, a2; /* these are all s6.25 format */
int32_t b0, b1, b2;
/* [0.1 .. 40] */
- b0 = FRACMUL(A, ap1 - FRACMUL(am1, cs) + twosqrtalpha) << 2;
+ b0 = FRACMUL_SHL(A, ap1 - FRACMUL(am1, cs) + twosqrtalpha, 2);
/* [-16 .. 63.4] */
- b1 = FRACMUL(A, am1 - FRACMUL(ap1, cs)) << 3;
+ b1 = FRACMUL_SHL(A, am1 - FRACMUL(ap1, cs), 3);
/* [0 .. 31.7] */
- b2 = FRACMUL(A, ap1 - FRACMUL(am1, cs) - twosqrtalpha) << 2;
+ b2 = FRACMUL_SHL(A, ap1 - FRACMUL(am1, cs) - twosqrtalpha, 2);
/* [0.5 .. 10] */
a0 = ap1 + FRACMUL(am1, cs) + twosqrtalpha;
/* [-16 .. 4] */
@@ -276,11 +221,13 @@ void eq_ls_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
/* [0 .. 8] */
a2 = ap1 + FRACMUL(am1, cs) - twosqrtalpha;
- c[0] = DIV64(b0, a0, 26); /* [0.06 .. 15.9] */
- c[1] = DIV64(b1, a0, 26); /* [-2 .. 31.7] */
- c[2] = DIV64(b2, a0, 26); /* [0 .. 15.9] */
- c[3] = DIV64(-a1, a0, 26); /* [-2 .. 2] */
- c[4] = DIV64(-a2, a0, 26); /* [0 .. 1] */
+ /* [0.1 .. 1.99] */
+ const long rcp_a0 = DIV64(1, a0, 55); /* s1.30 */
+ *c++ = FRACMUL_SHL(b0, rcp_a0, 2); /* [0.06 .. 15.9] */
+ *c++ = FRACMUL_SHL(b1, rcp_a0, 2); /* [-2 .. 31.7] */
+ *c++ = FRACMUL_SHL(b2, rcp_a0, 2); /* [0 .. 15.9] */
+ *c++ = FRACMUL_SHL(-a1, rcp_a0, 2); /* [-2 .. 2] */
+ *c++ = FRACMUL_SHL(-a2, rcp_a0, 2); /* [0 .. 1] */
}
/**
@@ -290,21 +237,22 @@ void eq_ls_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
void eq_hs_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
{
long cs;
- const int one = 1 << 25; /* s6.25 */
- const int A = dbtoA(db);
- const int alpha = DIV64(fsincos(cutoff, &cs), 2*Q, 15); /* s1.30 */
- const int ap1 = (A >> 4) + one;
- const int am1 = (A >> 4) - one;
- const int twosqrtalpha = 2*FRACMUL(fsqrt(A >> 3, 26), alpha);
+ const long one = 1 << 25; /* s6.25 */
+ const long sqrtA = get_replaygain_int(db*5/2) << 2; /* 10^(db/80), s5.26 */
+ const long A = FRACMUL_SHL(sqrtA, sqrtA, 8); /* s2.29 */
+ const long alpha = fsincos(cutoff, &cs)/(2*Q)*10 >> 1; /* s1.30 */
+ const long ap1 = (A >> 4) + one;
+ const long am1 = (A >> 4) - one;
+ const long twosqrtalpha = 2*FRACMUL(sqrtA, alpha);
int32_t a0, a1, a2; /* these are all s6.25 format */
int32_t b0, b1, b2;
/* [0.1 .. 40] */
- b0 = FRACMUL(A, ap1 + FRACMUL(am1, cs) + twosqrtalpha) << 2;
+ b0 = FRACMUL_SHL(A, ap1 + FRACMUL(am1, cs) + twosqrtalpha, 2);
/* [-63.5 .. 16] */
- b1 = -FRACMUL(A, am1 + FRACMUL(ap1, cs)) << 3;
+ b1 = -FRACMUL_SHL(A, am1 + FRACMUL(ap1, cs), 3);
/* [0 .. 32] */
- b2 = FRACMUL(A, ap1 + FRACMUL(am1, cs) - twosqrtalpha) << 2;
+ b2 = FRACMUL_SHL(A, ap1 + FRACMUL(am1, cs) - twosqrtalpha, 2);
/* [0.5 .. 10] */
a0 = ap1 - FRACMUL(am1, cs) + twosqrtalpha;
/* [-4 .. 16] */
@@ -312,13 +260,20 @@ void eq_hs_coefs(unsigned long cutoff, unsigned long Q, long db, int32_t *c)
/* [0 .. 8] */
a2 = ap1 - FRACMUL(am1, cs) - twosqrtalpha;
- c[0] = DIV64(b0, a0, 26); /* [0 .. 16] */
- c[1] = DIV64(b1, a0, 26); /* [-31.7 .. 2] */
- c[2] = DIV64(b2, a0, 26); /* [0 .. 16] */
- c[3] = DIV64(-a1, a0, 26); /* [-2 .. 2] */
- c[4] = DIV64(-a2, a0, 26); /* [0 .. 1] */
+ /* [0.1 .. 1.99] */
+ const long rcp_a0 = DIV64(1, a0, 55); /* s1.30 */
+ *c++ = FRACMUL_SHL(b0, rcp_a0, 2); /* [0 .. 16] */
+ *c++ = FRACMUL_SHL(b1, rcp_a0, 2); /* [-31.7 .. 2] */
+ *c++ = FRACMUL_SHL(b2, rcp_a0, 2); /* [0 .. 16] */
+ *c++ = FRACMUL_SHL(-a1, rcp_a0, 2); /* [-2 .. 2] */
+ *c++ = FRACMUL_SHL(-a2, rcp_a0, 2); /* [0 .. 1] */
}
+/* We realise the filters as a second order direct form 1 structure. Direct
+ * form 1 was chosen because of better numerical properties for fixed point
+ * implementations.
+ */
+
#if (!defined(CPU_COLDFIRE) && !defined(CPU_ARM)) || defined(SIMULATOR)
void eq_filter(int32_t **x, struct eqfilter *f, unsigned num,
unsigned channels, unsigned shift)
diff --git a/apps/plugins/lib/fixedpoint.c b/apps/plugins/lib/fixedpoint.c
index 914bc8c02a..9c34c2a0b7 100644
--- a/apps/plugins/lib/fixedpoint.c
+++ b/apps/plugins/lib/fixedpoint.c
@@ -117,3 +117,22 @@ long fsincos(unsigned long phase, long *cos)
return y;
}
+
+/**
+ * Fixed point square root via Newton-Raphson.
+ * @param a square root argument.
+ * @param fracbits specifies number of fractional bits in argument.
+ * @return Square root of argument in same fixed point format as input.
+ */
+long fsqrt(long a, unsigned int fracbits)
+{
+ long b = a/2 + (1 << fracbits); /* initial approximation */
+ unsigned n;
+ const unsigned iterations = 4;
+
+ for (n = 0; n < iterations; ++n)
+ b = (b + DIV64(a, b, fracbits))/2;
+
+ return b;
+}
+
diff --git a/apps/plugins/lib/fixedpoint.h b/apps/plugins/lib/fixedpoint.h
index 065f9fbb43..ff773cb0c5 100644
--- a/apps/plugins/lib/fixedpoint.h
+++ b/apps/plugins/lib/fixedpoint.h
@@ -20,3 +20,5 @@
****************************************************************************/
long fsincos(unsigned long phase, long *cos);
+long fsqrt(long a, unsigned int fracbits);
+