Name: LOG2.ASM
         Type: Assembler Macro
      Version: 1.0
  Last Change: 26-Jan-87

 This macro will take the log2 of a number by polynomial approximation.

        LOG2(x)= 4.0* (-.3372223 x*x + .9981958 x - .6626105)

 This polynomial will give approximately 8 significant bits of accuracy.
 This is valid for .5<= x <= 1.

 The input value is put into x0, the output value is in register A.
 Register R1 initially points to the coefficients in y memory in
 the order:a1,a2,a0.

       R1
       |
       v
 y:.9981958,-.3372223,-.6626105         
       a1       a2        a0

 Benchmarks for this macro is 7 cycles, 7 instructions.
 The library program LOG2T demonstrates how to use the LOG2 macro.