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
