Fix FS#11539. Undo r23967 and use another way to achieve results for negative exponents for pow(2,x). This solves heavy distortions on some aac encoded files and clicks/noise on track change.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27941 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 51 insertions, 99 deletions

diff --git a/apps/codecs/libfaad/common.c b/apps/codecs/libfaad/common.c
index c838c88d33..0e49896908 100644
--- a/apps/codecs/libfaad/common.c
+++ b/apps/codecs/libfaad/common.c
@@ -248,78 +248,33 @@ uint32_t random_int(void)
 #define TABLE_BITS 6
 /* just take the maximum number of bits for interpolation */
 #define INTERP_BITS (REAL_BITS-TABLE_BITS)
-/* precision of values in pow2_tab */
-#define POWTBL_BITS (31-(INTERP_BITS))
-#define POWTBL_PRECIS (1U<<(POWTBL_BITS))
-static const uint32_t pow2_tab[] ICONST_ATTR = {
-    UFIX_CONST(1.000000000000000,POWTBL_PRECIS),
-    UFIX_CONST(1.010889286051701,POWTBL_PRECIS),
-    UFIX_CONST(1.021897148654117,POWTBL_PRECIS),
-    UFIX_CONST(1.033024879021228,POWTBL_PRECIS),
-    UFIX_CONST(1.044273782427414,POWTBL_PRECIS),
-    UFIX_CONST(1.055645178360557,POWTBL_PRECIS),
-    UFIX_CONST(1.067140400676824,POWTBL_PRECIS),
-    UFIX_CONST(1.078760797757120,POWTBL_PRECIS),
-    UFIX_CONST(1.090507732665258,POWTBL_PRECIS),
-    UFIX_CONST(1.102382583307841,POWTBL_PRECIS),
-    UFIX_CONST(1.114386742595892,POWTBL_PRECIS),
-    UFIX_CONST(1.126521618608242,POWTBL_PRECIS),
-    UFIX_CONST(1.138788634756692,POWTBL_PRECIS),
-    UFIX_CONST(1.151189229952983,POWTBL_PRECIS),
-    UFIX_CONST(1.163724858777578,POWTBL_PRECIS),
-    UFIX_CONST(1.176396991650281,POWTBL_PRECIS),
-    UFIX_CONST(1.189207115002721,POWTBL_PRECIS),
-    UFIX_CONST(1.202156731452703,POWTBL_PRECIS),
-    UFIX_CONST(1.215247359980469,POWTBL_PRECIS),
-    UFIX_CONST(1.228480536106870,POWTBL_PRECIS),
-    UFIX_CONST(1.241857812073484,POWTBL_PRECIS),
-    UFIX_CONST(1.255380757024691,POWTBL_PRECIS),
-    UFIX_CONST(1.269050957191733,POWTBL_PRECIS),
-    UFIX_CONST(1.282870016078778,POWTBL_PRECIS),
-    UFIX_CONST(1.296839554651010,POWTBL_PRECIS),
-    UFIX_CONST(1.310961211524764,POWTBL_PRECIS),
-    UFIX_CONST(1.325236643159741,POWTBL_PRECIS),
-    UFIX_CONST(1.339667524053303,POWTBL_PRECIS),
-    UFIX_CONST(1.354255546936893,POWTBL_PRECIS),
-    UFIX_CONST(1.369002422974591,POWTBL_PRECIS),
-    UFIX_CONST(1.383909881963832,POWTBL_PRECIS),
-    UFIX_CONST(1.398979672538311,POWTBL_PRECIS),
-    UFIX_CONST(1.414213562373095,POWTBL_PRECIS),
-    UFIX_CONST(1.429613338391970,POWTBL_PRECIS),
-    UFIX_CONST(1.445180806977047,POWTBL_PRECIS),
-    UFIX_CONST(1.460917794180647,POWTBL_PRECIS),
-    UFIX_CONST(1.476826145939499,POWTBL_PRECIS),
-    UFIX_CONST(1.492907728291265,POWTBL_PRECIS),
-    UFIX_CONST(1.509164427593423,POWTBL_PRECIS),
-    UFIX_CONST(1.525598150744538,POWTBL_PRECIS),
-    UFIX_CONST(1.542210825407941,POWTBL_PRECIS),
-    UFIX_CONST(1.559004400237837,POWTBL_PRECIS),
-    UFIX_CONST(1.575980845107887,POWTBL_PRECIS),
-    UFIX_CONST(1.593142151342267,POWTBL_PRECIS),
-    UFIX_CONST(1.610490331949254,POWTBL_PRECIS),
-    UFIX_CONST(1.628027421857348,POWTBL_PRECIS),
-    UFIX_CONST(1.645755478153965,POWTBL_PRECIS),
-    UFIX_CONST(1.663676580326736,POWTBL_PRECIS),
-    UFIX_CONST(1.681792830507429,POWTBL_PRECIS),
-    UFIX_CONST(1.700106353718524,POWTBL_PRECIS),
-    UFIX_CONST(1.718619298122478,POWTBL_PRECIS),
-    UFIX_CONST(1.737333835273706,POWTBL_PRECIS),
-    UFIX_CONST(1.756252160373300,POWTBL_PRECIS),
-    UFIX_CONST(1.775376492526521,POWTBL_PRECIS),
-    UFIX_CONST(1.794709075003107,POWTBL_PRECIS),
-    UFIX_CONST(1.814252175500399,POWTBL_PRECIS),
-    UFIX_CONST(1.834008086409342,POWTBL_PRECIS),
-    UFIX_CONST(1.853979125083386,POWTBL_PRECIS),
-    UFIX_CONST(1.874167634110300,POWTBL_PRECIS),
-    UFIX_CONST(1.894575981586966,POWTBL_PRECIS),
-    UFIX_CONST(1.915206561397147,POWTBL_PRECIS),
-    UFIX_CONST(1.936061793492294,POWTBL_PRECIS),
-    UFIX_CONST(1.957144124175400,POWTBL_PRECIS),
-    UFIX_CONST(1.978456026387951,POWTBL_PRECIS),
-    UFIX_CONST(2.000000000000000,POWTBL_PRECIS)
+
+static const real_t pow2_tab[] = {
+    REAL_CONST(1.000000000000000), REAL_CONST(1.010889286051701), REAL_CONST(1.021897148654117),
+    REAL_CONST(1.033024879021228), REAL_CONST(1.044273782427414), REAL_CONST(1.055645178360557),
+    REAL_CONST(1.067140400676824), REAL_CONST(1.078760797757120), REAL_CONST(1.090507732665258),
+    REAL_CONST(1.102382583307841), REAL_CONST(1.114386742595892), REAL_CONST(1.126521618608242),
+    REAL_CONST(1.138788634756692), REAL_CONST(1.151189229952983), REAL_CONST(1.163724858777578),
+    REAL_CONST(1.176396991650281), REAL_CONST(1.189207115002721), REAL_CONST(1.202156731452703),
+    REAL_CONST(1.215247359980469), REAL_CONST(1.228480536106870), REAL_CONST(1.241857812073484),
+    REAL_CONST(1.255380757024691), REAL_CONST(1.269050957191733), REAL_CONST(1.282870016078778),
+    REAL_CONST(1.296839554651010), REAL_CONST(1.310961211524764), REAL_CONST(1.325236643159741),
+    REAL_CONST(1.339667524053303), REAL_CONST(1.354255546936893), REAL_CONST(1.369002422974591),
+    REAL_CONST(1.383909881963832), REAL_CONST(1.398979672538311), REAL_CONST(1.414213562373095),
+    REAL_CONST(1.429613338391970), REAL_CONST(1.445180806977047), REAL_CONST(1.460917794180647),
+    REAL_CONST(1.476826145939499), REAL_CONST(1.492907728291265), REAL_CONST(1.509164427593423),
+    REAL_CONST(1.525598150744538), REAL_CONST(1.542210825407941), REAL_CONST(1.559004400237837),
+    REAL_CONST(1.575980845107887), REAL_CONST(1.593142151342267), REAL_CONST(1.610490331949254),
+    REAL_CONST(1.628027421857348), REAL_CONST(1.645755478153965), REAL_CONST(1.663676580326736),
+    REAL_CONST(1.681792830507429), REAL_CONST(1.700106353718524), REAL_CONST(1.718619298122478),
+    REAL_CONST(1.737333835273706), REAL_CONST(1.756252160373300), REAL_CONST(1.775376492526521),
+    REAL_CONST(1.794709075003107), REAL_CONST(1.814252175500399), REAL_CONST(1.834008086409342),
+    REAL_CONST(1.853979125083386), REAL_CONST(1.874167634110300), REAL_CONST(1.894575981586966),
+    REAL_CONST(1.915206561397147), REAL_CONST(1.936061793492294), REAL_CONST(1.957144124175400),
+    REAL_CONST(1.978456026387951), REAL_CONST(2.000000000000000)
 };
 
-static const real_t log2_tab[] ICONST_ATTR_FAAD_LARGE_IRAM = {
+static const real_t log2_tab[] = {
     REAL_CONST(0.000000000000000), REAL_CONST(0.022367813028455), REAL_CONST(0.044394119358453),
     REAL_CONST(0.066089190457772), REAL_CONST(0.087462841250339), REAL_CONST(0.108524456778169),
     REAL_CONST(0.129283016944966), REAL_CONST(0.149747119504682), REAL_CONST(0.169925001442312),
@@ -356,19 +311,26 @@ uint32_t pow2_fix(real_t val)
     int32_t rest = val - (whole << REAL_BITS);
 
     /* index into pow2_tab */
-    int32_t index = rest >> (REAL_BITS-TABLE_BITS);
+    int32_t index = (rest >> (REAL_BITS-TABLE_BITS)) & ((1<<TABLE_BITS)-1);
+
+
+    if (val == 0)
+        return (1<<REAL_BITS);
 
     /* leave INTERP_BITS bits */
     index_frac = rest >> (REAL_BITS-TABLE_BITS-INTERP_BITS);
     index_frac = index_frac & ((1<<INTERP_BITS)-1);
 
-    x1 = pow2_tab[index & ((1<<TABLE_BITS)-1)];
-    x2 = pow2_tab[(index & ((1<<TABLE_BITS)-1)) + 1];
-    errcorr = ( (index_frac*(x2-x1)));
+    if (whole >= 0)
+        retval = REAL_CONST(1) << whole;
+    else
+        retval = REAL_CONST(1) >> -whole;
 
-    retval = errcorr + (x1<<INTERP_BITS);
+    x1 = pow2_tab[index    ];
+    x2 = pow2_tab[index + 1];
+    errcorr = (index_frac*(x2-x1)) >> INTERP_BITS;
 
-    retval = DESCALE_SHIFT(retval, whole, POWTBL_BITS + INTERP_BITS - REAL_BITS);
+    retval = MUL_R(retval, (errcorr + x1));
 
     return retval;
 }
@@ -385,19 +347,26 @@ uint32_t pow2_int(real_t val)
     int32_t rest = val - (whole << REAL_BITS);
 
     /* index into pow2_tab */
-    int32_t index = rest >> (REAL_BITS-TABLE_BITS);
+    int32_t index = (rest >> (REAL_BITS-TABLE_BITS)) & ((1<<TABLE_BITS)-1);
+
+
+    if (val == 0)
+        return 1;
 
     /* leave INTERP_BITS bits */
     index_frac = rest >> (REAL_BITS-TABLE_BITS-INTERP_BITS);
     index_frac = index_frac & ((1<<INTERP_BITS)-1);
 
-    x1 = pow2_tab[index & ((1<<TABLE_BITS)-1)];
-    x2 = pow2_tab[(index & ((1<<TABLE_BITS)-1)) + 1];
-    errcorr = ( (index_frac*(x2-x1)));
+    if (whole >= 0)
+        retval = 1 << whole;
+    else
+        retval = 1 >> -whole;
 
-    retval = errcorr + (x1<<INTERP_BITS);
+    x1 = pow2_tab[index    ];
+    x2 = pow2_tab[index + 1];
+    errcorr = (index_frac*(x2-x1)) >> INTERP_BITS;
 
-    retval = DESCALE_SHIFT(retval, whole, POWTBL_BITS + INTERP_BITS);
+    retval = MUL_R(retval, (errcorr + x1));
 
     return retval;
 }
diff --git a/apps/codecs/libfaad/fixed.h b/apps/codecs/libfaad/fixed.h
index 6cda967399..ee06dc4421 100644
--- a/apps/codecs/libfaad/fixed.h
+++ b/apps/codecs/libfaad/fixed.h
@@ -49,7 +49,6 @@ extern "C" {
 
 typedef int32_t real_t;
 
-#define UFIX_CONST(A,PRECISION) ((uint32_t)((A)*(PRECISION)+0.5))
 #define FIX_CONST(A,PRECISION) (((A) >= 0) ? ((real_t)((A)*(PRECISION)+0.5)) : ((real_t)((A)*(PRECISION)-0.5)))
 #define REAL_CONST(A) FIX_CONST((A),(REAL_PRECISION))
 #define COEF_CONST(A) FIX_CONST((A),(COEF_PRECISION))
@@ -129,8 +128,6 @@ static INLINE void ComplexMult(real_t *y1, real_t *y2,
   #define MUL_Q2(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (Q2_BITS-1))) >> Q2_BITS)
   #define MUL_SHIFT6(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (6-1))) >> 6)
   #define MUL_SHIFT23(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (23-1))) >> 23)
-  #define DESCALE(A,S) ((S)>0?(((A)>>((S)-1))+1)>>1:(A)<<-(S))
-  #define DESCALE_SHIFT(A,SH,SC) DESCALE((A),(SC)-(SH))
 
 #elif defined(__GNUC__) && defined (__arm__)
 
@@ -208,18 +205,6 @@ static INLINE void ComplexMult(real_t *y1, real_t *y2,
     *y2 = yt2 << (FRAC_SIZE-FRAC_BITS);
 }
 
-static inline real_t DESCALE_SHIFT(unsigned val, int shift, int scale)
-{
-    unsigned out;
-    if ((out = val >> (scale - shift - 1)))
-    {
-        out++;
-        out >>= 1;
-    } else
-        out = val << (shift - scale);
-    return out;
-}
-
 #else
 
   /* multiply with real shift */
@@ -240,8 +225,6 @@ static inline real_t DESCALE_SHIFT(unsigned val, int shift, int scale)
   #define MUL_Q2(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (Q2_BITS-1))) >> Q2_BITS)
   #define MUL_SHIFT6(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (6-1))) >> 6)
   #define MUL_SHIFT23(A,B) (real_t)(((int64_t)(A)*(int64_t)(B)+(1 << (23-1))) >> 23)
-  #define DESCALE(A,S) ((S)>0?(((A)>>((S)-1))+1)>>1:(A)<<-(S))
-  #define DESCALE_SHIFT(A,SH,SC) DESCALE((A),(SC)-(SH))
 
 /* Complex multiplication */
 static INLINE void ComplexMult(real_t *y1, real_t *y2,