forked from len0rd/rockbox
Libfaad pow2/log2 improvements:
Correct pow2_* to calculate correct output for input < 0.0 or between 0.0 and 1.0 instead of returning 0. This will change output, but the float version of this codec uses pow(2.0,x) in place of these functions, so this behavior was probably a bug Replace 64-bit multiply in pow2_* with left or right shift by whole part of input, rounding if shifting right. An ARM-specific optimized version is provided as a C inline function, other targets use a C macro. Increase constant size of table for pow2 to improve accuracy, also avoid early truncation in linear interpolation of result. Move constant tables for pow2 and log2 to iram. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@23967 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andrew Mahone
parent
7668e3fe51
commit
af5bad46d8
3 changed files with 105 additions and 64 deletions
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@ -248,33 +248,78 @@ uint32_t random_int(void)
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#define TABLE_BITS 6
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/* just take the maximum number of bits for interpolation */
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#define INTERP_BITS (REAL_BITS-TABLE_BITS)
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static const real_t pow2_tab[] = {
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REAL_CONST(1.000000000000000), REAL_CONST(1.010889286051701), REAL_CONST(1.021897148654117),
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REAL_CONST(1.033024879021228), REAL_CONST(1.044273782427414), REAL_CONST(1.055645178360557),
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REAL_CONST(1.067140400676824), REAL_CONST(1.078760797757120), REAL_CONST(1.090507732665258),
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REAL_CONST(1.102382583307841), REAL_CONST(1.114386742595892), REAL_CONST(1.126521618608242),
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REAL_CONST(1.138788634756692), REAL_CONST(1.151189229952983), REAL_CONST(1.163724858777578),
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REAL_CONST(1.176396991650281), REAL_CONST(1.189207115002721), REAL_CONST(1.202156731452703),
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REAL_CONST(1.215247359980469), REAL_CONST(1.228480536106870), REAL_CONST(1.241857812073484),
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REAL_CONST(1.255380757024691), REAL_CONST(1.269050957191733), REAL_CONST(1.282870016078778),
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REAL_CONST(1.296839554651010), REAL_CONST(1.310961211524764), REAL_CONST(1.325236643159741),
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REAL_CONST(1.339667524053303), REAL_CONST(1.354255546936893), REAL_CONST(1.369002422974591),
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REAL_CONST(1.383909881963832), REAL_CONST(1.398979672538311), REAL_CONST(1.414213562373095),
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REAL_CONST(1.429613338391970), REAL_CONST(1.445180806977047), REAL_CONST(1.460917794180647),
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REAL_CONST(1.476826145939499), REAL_CONST(1.492907728291265), REAL_CONST(1.509164427593423),
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REAL_CONST(1.525598150744538), REAL_CONST(1.542210825407941), REAL_CONST(1.559004400237837),
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REAL_CONST(1.575980845107887), REAL_CONST(1.593142151342267), REAL_CONST(1.610490331949254),
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REAL_CONST(1.628027421857348), REAL_CONST(1.645755478153965), REAL_CONST(1.663676580326736),
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REAL_CONST(1.681792830507429), REAL_CONST(1.700106353718524), REAL_CONST(1.718619298122478),
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REAL_CONST(1.737333835273706), REAL_CONST(1.756252160373300), REAL_CONST(1.775376492526521),
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REAL_CONST(1.794709075003107), REAL_CONST(1.814252175500399), REAL_CONST(1.834008086409342),
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REAL_CONST(1.853979125083386), REAL_CONST(1.874167634110300), REAL_CONST(1.894575981586966),
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REAL_CONST(1.915206561397147), REAL_CONST(1.936061793492294), REAL_CONST(1.957144124175400),
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REAL_CONST(1.978456026387951), REAL_CONST(2.000000000000000)
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/* precision of values in pow2_tab */
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#define POWTBL_BITS (31-(INTERP_BITS))
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#define POWTBL_PRECIS (1U<<(POWTBL_BITS))
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static const uint32_t pow2_tab[] ICONST_ATTR = {
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UFIX_CONST(1.000000000000000,POWTBL_PRECIS),
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UFIX_CONST(1.010889286051701,POWTBL_PRECIS),
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UFIX_CONST(1.021897148654117,POWTBL_PRECIS),
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UFIX_CONST(1.033024879021228,POWTBL_PRECIS),
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UFIX_CONST(1.044273782427414,POWTBL_PRECIS),
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UFIX_CONST(1.055645178360557,POWTBL_PRECIS),
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UFIX_CONST(1.067140400676824,POWTBL_PRECIS),
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UFIX_CONST(1.078760797757120,POWTBL_PRECIS),
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UFIX_CONST(1.090507732665258,POWTBL_PRECIS),
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UFIX_CONST(1.102382583307841,POWTBL_PRECIS),
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UFIX_CONST(1.114386742595892,POWTBL_PRECIS),
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UFIX_CONST(1.126521618608242,POWTBL_PRECIS),
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UFIX_CONST(1.138788634756692,POWTBL_PRECIS),
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UFIX_CONST(1.151189229952983,POWTBL_PRECIS),
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UFIX_CONST(1.163724858777578,POWTBL_PRECIS),
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UFIX_CONST(1.176396991650281,POWTBL_PRECIS),
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UFIX_CONST(1.189207115002721,POWTBL_PRECIS),
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UFIX_CONST(1.202156731452703,POWTBL_PRECIS),
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UFIX_CONST(1.215247359980469,POWTBL_PRECIS),
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UFIX_CONST(1.228480536106870,POWTBL_PRECIS),
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UFIX_CONST(1.241857812073484,POWTBL_PRECIS),
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UFIX_CONST(1.255380757024691,POWTBL_PRECIS),
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UFIX_CONST(1.269050957191733,POWTBL_PRECIS),
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UFIX_CONST(1.282870016078778,POWTBL_PRECIS),
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UFIX_CONST(1.296839554651010,POWTBL_PRECIS),
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UFIX_CONST(1.310961211524764,POWTBL_PRECIS),
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UFIX_CONST(1.325236643159741,POWTBL_PRECIS),
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UFIX_CONST(1.339667524053303,POWTBL_PRECIS),
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UFIX_CONST(1.354255546936893,POWTBL_PRECIS),
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UFIX_CONST(1.369002422974591,POWTBL_PRECIS),
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UFIX_CONST(1.383909881963832,POWTBL_PRECIS),
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UFIX_CONST(1.398979672538311,POWTBL_PRECIS),
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UFIX_CONST(1.414213562373095,POWTBL_PRECIS),
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UFIX_CONST(1.429613338391970,POWTBL_PRECIS),
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UFIX_CONST(1.445180806977047,POWTBL_PRECIS),
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UFIX_CONST(1.460917794180647,POWTBL_PRECIS),
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UFIX_CONST(1.476826145939499,POWTBL_PRECIS),
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UFIX_CONST(1.492907728291265,POWTBL_PRECIS),
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UFIX_CONST(1.509164427593423,POWTBL_PRECIS),
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UFIX_CONST(1.525598150744538,POWTBL_PRECIS),
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UFIX_CONST(1.542210825407941,POWTBL_PRECIS),
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UFIX_CONST(1.559004400237837,POWTBL_PRECIS),
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UFIX_CONST(1.575980845107887,POWTBL_PRECIS),
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UFIX_CONST(1.593142151342267,POWTBL_PRECIS),
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UFIX_CONST(1.610490331949254,POWTBL_PRECIS),
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UFIX_CONST(1.628027421857348,POWTBL_PRECIS),
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UFIX_CONST(1.645755478153965,POWTBL_PRECIS),
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UFIX_CONST(1.663676580326736,POWTBL_PRECIS),
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UFIX_CONST(1.681792830507429,POWTBL_PRECIS),
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UFIX_CONST(1.700106353718524,POWTBL_PRECIS),
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UFIX_CONST(1.718619298122478,POWTBL_PRECIS),
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UFIX_CONST(1.737333835273706,POWTBL_PRECIS),
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UFIX_CONST(1.756252160373300,POWTBL_PRECIS),
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UFIX_CONST(1.775376492526521,POWTBL_PRECIS),
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UFIX_CONST(1.794709075003107,POWTBL_PRECIS),
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UFIX_CONST(1.814252175500399,POWTBL_PRECIS),
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UFIX_CONST(1.834008086409342,POWTBL_PRECIS),
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UFIX_CONST(1.853979125083386,POWTBL_PRECIS),
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UFIX_CONST(1.874167634110300,POWTBL_PRECIS),
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UFIX_CONST(1.894575981586966,POWTBL_PRECIS),
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UFIX_CONST(1.915206561397147,POWTBL_PRECIS),
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UFIX_CONST(1.936061793492294,POWTBL_PRECIS),
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UFIX_CONST(1.957144124175400,POWTBL_PRECIS),
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UFIX_CONST(1.978456026387951,POWTBL_PRECIS),
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UFIX_CONST(2.000000000000000,POWTBL_PRECIS)
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};
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static const real_t log2_tab[] = {
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static const real_t log2_tab[] ICONST_ATTR = {
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REAL_CONST(0.000000000000000), REAL_CONST(0.022367813028455), REAL_CONST(0.044394119358453),
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REAL_CONST(0.066089190457772), REAL_CONST(0.087462841250339), REAL_CONST(0.108524456778169),
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REAL_CONST(0.129283016944966), REAL_CONST(0.149747119504682), REAL_CONST(0.169925001442312),
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@ -299,12 +344,12 @@ static const real_t log2_tab[] = {
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REAL_CONST(0.988684686772166), REAL_CONST(1.000000000000000)
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};
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real_t pow2_fix(real_t val)
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uint32_t pow2_fix(real_t val)
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{
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uint32_t x1, x2;
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uint32_t errcorr;
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uint32_t index_frac;
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real_t retval;
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uint32_t retval;
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int32_t whole = (val >> REAL_BITS);
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/* rest = [0..1] */
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@ -313,41 +358,27 @@ real_t pow2_fix(real_t val)
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/* index into pow2_tab */
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int32_t index = rest >> (REAL_BITS-TABLE_BITS);
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if (val == 0)
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return (1<<REAL_BITS);
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/* leave INTERP_BITS bits */
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index_frac = rest >> (REAL_BITS-TABLE_BITS-INTERP_BITS);
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index_frac = index_frac & ((1<<INTERP_BITS)-1);
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if (whole > 0)
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{
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retval = 1 << whole;
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} else {
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retval = REAL_CONST(1) >> -whole;
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}
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x1 = pow2_tab[index & ((1<<TABLE_BITS)-1)];
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x2 = pow2_tab[(index & ((1<<TABLE_BITS)-1)) + 1];
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errcorr = ( (index_frac*(x2-x1))) >> INTERP_BITS;
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errcorr = ( (index_frac*(x2-x1)));
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if (whole > 0)
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{
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retval = retval * (errcorr + x1);
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} else {
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retval = MUL_R(retval, (errcorr + x1));
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}
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retval = errcorr + (x1<<INTERP_BITS);
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retval = DESCALE_SHIFT(retval, whole, POWTBL_BITS + INTERP_BITS - REAL_BITS);
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return retval;
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}
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int32_t pow2_int(real_t val)
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uint32_t pow2_int(real_t val)
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{
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uint32_t x1, x2;
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uint32_t errcorr;
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uint32_t index_frac;
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real_t retval;
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uint32_t retval;
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int32_t whole = (val >> REAL_BITS);
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/* rest = [0..1] */
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@ -356,24 +387,17 @@ int32_t pow2_int(real_t val)
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/* index into pow2_tab */
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int32_t index = rest >> (REAL_BITS-TABLE_BITS);
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if (val == 0)
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return 1;
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/* leave INTERP_BITS bits */
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index_frac = rest >> (REAL_BITS-TABLE_BITS-INTERP_BITS);
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index_frac = index_frac & ((1<<INTERP_BITS)-1);
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if (whole > 0)
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retval = 1 << whole;
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else
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retval = 0;
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x1 = pow2_tab[index & ((1<<TABLE_BITS)-1)];
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x2 = pow2_tab[(index & ((1<<TABLE_BITS)-1)) + 1];
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errcorr = ( (index_frac*(x2-x1))) >> INTERP_BITS;
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errcorr = ( (index_frac*(x2-x1)));
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retval = MUL_R(retval, (errcorr + x1));
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retval = errcorr + (x1<<INTERP_BITS);
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retval = DESCALE_SHIFT(retval, whole, POWTBL_BITS + INTERP_BITS);
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return retval;
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}
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