#!/usr/bin/perl

die "\nPlease give me a name and a number, like:\n% ./base10to32bitandQscale.pl a0= 0.02345\n" if (! $ARGV[0]) ;
$COEFFbase10 = join ('',@ARGV) ;
if ($COEFFbase10 !~ /\s*(\S+)\s*=\s*(.*)/)  { die "\nPlease give me a name and a number, like:\n% ./base10to32bitandQscale.pl a0= 0.02345\n" ; } 
$NAME        = $1 ;
$COEFFbase10 = $2 ;
chomp $COEFFbase10 ;

# Get the coefficient, note if negative, strip minus sign
chomp $COEFFbase10 ;
$isneg = ($COEFFbase10 =~ /-/) ? "-" : "" ;
$COEFFbase10 =~ s/-// ;
$orig = $COEFFbase10 ;

# Multiply up by 2 until the value is 1023 or more. 1/1023 gives better
# than 0.1% accuracy. Record the multiplier.
$m = 0 ;
while ($COEFFbase10 < 1023) { $COEFFbase10 = 2 * $COEFFbase10 ; $m++ ; }
$n = $m ;


# Ignore (truncate) the fractional part that did not get multiplied up to
# the left of the decimal point, and return the coefficient * 2^n in base 2.
$AA = &dec2bin(int($COEFFbase10)) ;


# This is for presenting the base 2 representation of the original
# fractional number.
@c = split //,$AA ;
@c = reverse @c ; 
$j = 0 ;
for ($i=0;$i < 31;$i++)
{
if ($m == 0) {$f[$i] = '.' ;}
else {
  if   (defined $c[$i]) {$f[$i] = $c[$j] ; $j++ ; }
  else                  {$f[$i] = '0' ; }
  }
  $m-- ;
}
@f = reverse @f ;
$line = join ('',@f) ;

while (length $AA < 16) {$AA = "0"."$AA" ; }
# and in base 2 : $isneg"."$line" ;
# print "\n\/\/ Q = $n" ;
# print "\n\/\/ after being multiplied up by 2^$n" ;
# print "\n\/\/ in base 10 is : $isneg"."$COEFFbase10" ;
# print "\n\/\/ in 16-bits in base 2 is : $isneg"."$AA" ;


# Turn in into a string to do the 2's complement.
while (length $AA < 16) {$AA = "0"."$AA" ; }
@f = split //,$AA ;
if ($isneg) 
{
  for ($i=0; $i <= $#f ; $i++) { $f[$i] = ($f[$i] eq "1") ? '0' : '1' ;}
  $line = join @f ;
  for ($i=$#f ; $i >= 0; $i--)
  {
    if ($f[$i] eq '0') { $f[$i] = '1' ; last ; }
    else               { $f[$i] = '0' ; }
  }
}
$line = join ('',@f) ;
print "\n\/\/-------------------------------------------------------------" ;
print "\n Mult16bitByConstFixed $NAME"."_inst ( \t// $NAME = $isneg"."$orig" ;
print "\n   .Q     ('d$n),                \t//" ;
print "\n   .coeff (16'b$line),\t// ($NAME"."base2) x 2^$n" ;
print "\n   .B     (BBBBBBB$NAME),           \t//" ;
print "\n   .y     (yyyyyyy$NAME)            \t// y = coeff*B >>> Q" ;
print "\n ) ;\n" ;


# print "\n\/\/ and as a 32-bit 2's complement: $line\n" ;



#--------------------------------------------------------------------
sub dec2bin {
    my $str = unpack("B32", pack("N", shift));
    $str =~ s/^0+(?=\d)//;   # remove leading zeros
    return $str;
}