526b5580da
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21070 a1c6a512-1295-4272-9138-f99709370657
105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
#include <m_pd.h>
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#include <m_fixed.h>
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/* sigrsqrt - reciprocal square root good to 8 mantissa bits */
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#define DUMTAB1SIZE 256
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#define DUMTAB2SIZE 1024
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static float rsqrt_exptab[DUMTAB1SIZE], rsqrt_mantissatab[DUMTAB2SIZE];
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static void init_rsqrt(void)
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{
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int i;
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for (i = 0; i < DUMTAB1SIZE; i++)
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{
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float f;
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long l = (i ? (i == DUMTAB1SIZE-1 ? DUMTAB1SIZE-2 : i) : 1)<< 23;
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*(long *)(&f) = l;
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rsqrt_exptab[i] = 1./sqrt(f);
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}
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for (i = 0; i < DUMTAB2SIZE; i++)
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{
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float f = 1 + (1./DUMTAB2SIZE) * i;
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rsqrt_mantissatab[i] = 1./sqrt(f);
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}
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}
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/* these are used in externs like "bonk" */
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float q8_rsqrt(float f)
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{
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long l = *(long *)(&f);
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if (f < 0) return (0);
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else return (rsqrt_exptab[(l >> 23) & 0xff] *
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rsqrt_mantissatab[(l >> 13) & 0x3ff]);
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}
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float q8_sqrt(float f)
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{
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long l = *(long *)(&f);
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if (f < 0) return (0);
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else return (f * rsqrt_exptab[(l >> 23) & 0xff] *
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rsqrt_mantissatab[(l >> 13) & 0x3ff]);
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}
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/* the old names are OK unless we're in IRIX N32 */
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#ifndef N32
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float qsqrt(float f) {return (q8_sqrt(f)); }
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float qrsqrt(float f) {return (q8_rsqrt(f)); }
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#endif
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typedef struct sigrsqrt
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{
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t_object x_obj;
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float x_f;
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} t_sigrsqrt;
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static t_class *sigrsqrt_class;
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static void *sigrsqrt_new(void)
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{
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t_sigrsqrt *x = (t_sigrsqrt *)pd_new(sigrsqrt_class);
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outlet_new(&x->x_obj, gensym("signal"));
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x->x_f = 0;
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return (x);
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}
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static t_int *sigrsqrt_perform(t_int *w)
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{
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float *in = *(t_float **)(w+1), *out = *(t_float **)(w+2);
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t_int n = *(t_int *)(w+3);
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while (n--)
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{
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float f = *in;
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long l = *(long *)(in++);
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if (f < 0) *out++ = 0;
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else
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{
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float g = rsqrt_exptab[(l >> 23) & 0xff] *
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rsqrt_mantissatab[(l >> 13) & 0x3ff];
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*out++ = 1.5 * g - 0.5 * g * g * g * f;
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}
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}
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return (w + 4);
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}
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static void sigrsqrt_dsp(t_sigrsqrt *x, t_signal **sp)
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{
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dsp_add(sigrsqrt_perform, 3, sp[0]->s_vec, sp[1]->s_vec, sp[0]->s_n);
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}
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void rsqrt_tilde_setup(void)
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{
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init_rsqrt();
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sigrsqrt_class = class_new(gensym("rsqrt~"), (t_newmethod)sigrsqrt_new, 0,
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sizeof(t_sigrsqrt), 0, 0);
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/* an old name for it: */
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class_addcreator(sigrsqrt_new, gensym("q8_rsqrt~"), 0);
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CLASS_MAINSIGNALIN(sigrsqrt_class, t_sigrsqrt, x_f);
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class_addmethod(sigrsqrt_class, (t_method)sigrsqrt_dsp, gensym("dsp"), 0);
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}
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