5 -- | WavPack internal functions
6 module Codec.Audio.WavPack.Internal
22 import qualified Data.Vector.Unboxed as UV
23 import Prelude.Unicode
25 -- | Convert internal weights (which are normally +/-1024) to an 8-bit
26 -- signed character version for storage in metadata. The weights are
27 -- clipped here in the case they are outside that range.
28 packWeight ∷ Int16 → Word8
30 = let !w' | w > 1024 = 1024
33 !w'' | w' > 0 = w' - ((w' + 64) `shiftR` 7)
35 !w''' = (w'' + 4) `shiftR` 3
39 -- | Convert a packed weight to internal weight (+/-1024). Note that
40 -- the following equation /might not hold/ because 'packWeight' is
43 -- > unpackWeight . packWeight = id
45 unpackWeight ∷ Word8 → Int16
50 w'' = (fromIntegral w') `shiftL` 3
51 !w''' | w'' > 0 = w'' + ((w'' + 64) `shiftR` 7)
56 -- | Return the 'log2' for the specified 32-bit signed integer. All
57 -- input values are valid and the return values are in the range of
61 | n < 0 = fromIntegral $ negate $ log2 $ fromIntegral $ negate n
62 | otherwise = fromIntegral $ log2 $ fromIntegral n
64 -- | The concept of a base 2 logarithm is used in many parts of
65 -- WavPack. It is a way of sufficiently accurately representing 32-bit
66 -- signed and unsigned values storing only 16 bits (actually
67 -- fewer). It is also used in the hybrid mode for quickly comparing
68 -- the relative magnitude of large values (i.e. division) and
69 -- providing smooth exponentials using only addition.
71 -- These are not strict logarithms in that they become linear around
72 -- zero and can therefore represent both zero and negative
73 -- values. They have 8 bits of precision and in \"roundtrip\"
74 -- conversions the total error never exceeds 1 part in 225 except for
75 -- the cases of +\/-115 and +\/-195 (which error by 1).
77 -- This function returns the log2 for the specified 32-bit unsigned
78 -- value. The maximum value allowed is about 0xff800000 and returns
80 log2 ∷ Word32 → Word16
84 dbits = fromIntegral $ getNBits $ fromIntegral n'
85 !index = (n' `shiftL` fromIntegral (9 - dbits)) .&. 0xFF
86 !log2n = fromIntegral $ getLog2 $ fromIntegral index
88 (dbits `shiftL` 8) + log2n
91 dbits | n' < (1 `shiftL` 16)
92 = fromIntegral (getNBits $ fromIntegral $ n' `shiftR` 8) + 8
93 | n' < (1 `shiftL` 24)
94 = fromIntegral (getNBits $ fromIntegral $ n' `shiftR` 16) + 16
96 = fromIntegral (getNBits $ fromIntegral $ n' `shiftR` 24) + 24
97 !index = (n' `shiftR` fromIntegral (dbits - 9)) .&. 0xFF
98 !log2n = fromIntegral $ getLog2 $ fromIntegral index
100 (dbits `shiftL` 8) + log2n
103 n' = n + (n `shiftR` 9)
105 -- | Return the original integer represented by the supplied logarithm
106 -- (at least within the provided accuracy). The log is signed, but
107 -- since a full 32-bit value is returned this can be used for unsigned
108 -- conversions as well (i.e. the input range is -8192 to +8447).
109 exp2s ∷ Int16 → Int32
111 | l < 0 = fromIntegral $ negate $ exp2 $ fromIntegral $ negate l
112 | otherwise = fromIntegral $ exp2 $ fromIntegral l
114 -- | Return the original integer represented by the supplied logarithm
115 -- (at least within the provided accuracy).
116 exp2 ∷ Word16 → Word32
119 exp2l = fromIntegral (getExp2 $ fromIntegral $ l .&. 0xFF) .|. 0x100
121 l' = fromIntegral $ l `shiftR` 8
124 exp2l `shiftR` fromIntegral (9 - l')
126 exp2l `shiftL` fromIntegral (l' - 9)
128 -- | 'countBits' @av@ returns the number of bits that is required to
130 countBits ∷ Word32 → Word8
132 | av < (1 `shiftL` 8) = getNBits (fromIntegral av)
133 | av < (1 `shiftL` 16) = getNBits (fromIntegral (av `shiftR` 8)) + 8
134 | av < (1 `shiftL` 24) = getNBits (fromIntegral (av `shiftR` 16)) + 16
135 | otherwise = getNBits (fromIntegral (av `shiftR` 24)) + 24
137 getNBits ∷ Word8 → Word8
138 getNBits = UV.unsafeIndex nbitsTable ∘ fromIntegral
140 nbitsTable ∷ UV.Vector Word8
143 [ 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 -- 0 - 15
144 , 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 -- 16 - 31
145 , 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6 -- 32 - 47
146 , 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6 -- 48 - 63
147 , 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 -- 64 - 79
148 , 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 -- 80 - 95
149 , 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 -- 96 - 111
150 , 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 -- 112 - 127
151 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 128 - 143
152 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 144 - 159
153 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 160 - 175
154 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 176 - 191
155 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 192 - 207
156 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 208 - 223
157 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 224 - 239
158 , 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 -- 240 - 255
161 getLog2 ∷ Word8 → Word8
162 getLog2 = UV.unsafeIndex log2Table ∘ fromIntegral
164 log2Table ∷ UV.Vector Word8
167 [ 0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a, 0x0B, 0x0D, 0x0E, 0x10, 0x11, 0x12, 0x14, 0x15
168 , 0x16, 0x18, 0x19, 0x1a, 0x1C, 0x1D, 0x1E, 0x20, 0x21, 0x22, 0x24, 0x25, 0x26, 0x28, 0x29, 0x2a
169 , 0x2C, 0x2D, 0x2E, 0x2F, 0x31, 0x32, 0x33, 0x34, 0x36, 0x37, 0x38, 0x39, 0x3B, 0x3C, 0x3D, 0x3E
170 , 0x3F, 0x41, 0x42, 0x43, 0x44, 0x45, 0x47, 0x48, 0x49, 0x4a, 0x4B, 0x4D, 0x4E, 0x4F, 0x50, 0x51
171 , 0x52, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63
172 , 0x64, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x74, 0x75
173 , 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85
174 , 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95
175 , 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9B, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4
176 , 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xa9, 0xaa, 0xaB, 0xaC, 0xaD, 0xaE, 0xaF, 0xB0, 0xB1, 0xB2, 0xB2
177 , 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xB9, 0xBa, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF, 0xC0, 0xC0
178 , 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC6, 0xC7, 0xC8, 0xC9, 0xCa, 0xCB, 0xCB, 0xCC, 0xCD, 0xCE
179 , 0xCF, 0xD0, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD8, 0xD9, 0xDa, 0xDB
180 , 0xDC, 0xDC, 0xDD, 0xDE, 0xDF, 0xE0, 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE4, 0xE5, 0xE6, 0xE7, 0xE7
181 , 0xE8, 0xE9, 0xEa, 0xEa, 0xEB, 0xEC, 0xED, 0xEE, 0xEE, 0xEF, 0xF0, 0xF1, 0xF1, 0xF2, 0xF3, 0xF4
182 , 0xF4, 0xF5, 0xF6, 0xF7, 0xF7, 0xF8, 0xF9, 0xF9, 0xFa, 0xFB, 0xFC, 0xFC, 0xFD, 0xFE, 0xFF, 0xFF
185 getExp2 ∷ Word8 → Word8
186 getExp2 = UV.unsafeIndex exp2Table ∘ fromIntegral
188 exp2Table ∷ UV.Vector Word8
191 [ 0x00, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x08, 0x09, 0x0a, 0x0B
192 , 0x0B, 0x0C, 0x0D, 0x0E, 0x0E, 0x0F, 0x10, 0x10, 0x11, 0x12, 0x13, 0x13, 0x14, 0x15, 0x16, 0x16
193 , 0x17, 0x18, 0x19, 0x19, 0x1a, 0x1B, 0x1C, 0x1D, 0x1D, 0x1E, 0x1F, 0x20, 0x20, 0x21, 0x22, 0x23
194 , 0x24, 0x24, 0x25, 0x26, 0x27, 0x28, 0x28, 0x29, 0x2a, 0x2B, 0x2C, 0x2C, 0x2D, 0x2E, 0x2F, 0x30
195 , 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3a, 0x3B, 0x3C, 0x3D
196 , 0x3E, 0x3F, 0x40, 0x41, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4B
197 , 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a
198 , 0x5B, 0x5C, 0x5D, 0x5E, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69
199 , 0x6a, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79
200 , 0x7a, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x87, 0x88, 0x89, 0x8a
201 , 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92, 0x93, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9B
202 , 0x9C, 0x9D, 0x9F, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa8, 0xa9, 0xaa, 0xaB, 0xaC, 0xaD
203 , 0xaF, 0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB6, 0xB7, 0xB8, 0xB9, 0xBa, 0xBC, 0xBD, 0xBE, 0xBF, 0xC0
204 , 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC8, 0xC9, 0xCa, 0xCB, 0xCD, 0xCE, 0xCF, 0xD0, 0xD2, 0xD3, 0xD4
205 , 0xD6, 0xD7, 0xD8, 0xD9, 0xDB, 0xDC, 0xDD, 0xDE, 0xE0, 0xE1, 0xE2, 0xE4, 0xE5, 0xE6, 0xE8, 0xE9
206 , 0xEa, 0xEC, 0xED, 0xEE, 0xF0, 0xF1, 0xF2, 0xF4, 0xF5, 0xF6, 0xF8, 0xF9, 0xFa, 0xFC, 0xFD, 0xFF