text: 
  #include <stdbool.h>
  #include <stdint.h>
  #include "platform.h"
  #include "primitives.h"
  #include "internals.h"
  #include "specialize.h"
  #include "softfloat.h"
  
  float64_t f64_sqrt( float64_t a )
  {
      union ui64_f64 uA;
      uint_fast64_t uiA;
      bool signA;
      int_fast16_t expA;
      uint_fast64_t sigA, uiZ;
      struct exp16_sig64 normExpSig;
      int_fast16_t expZ;
      uint_fast32_t sigZ32;
      uint_fast64_t sigZ;
      struct uint128 term, rem;
      union ui64_f64 uZ;
  
      uA.f = a;
      uiA = uA.ui;
      signA = signF64UI( uiA );
      expA = expF64UI( uiA );
      sigA = fracF64UI( uiA );
      if ( expA == 0x7FF ) {
          if ( sigA ) {
              uiZ = softfloat_propagateNaNF64UI( uiA, 0 );
              goto uiZ;
          }
          if ( ! signA ) return a;
          goto invalid;
      }
      if ( signA ) {
          if ( ! ( expA | sigA ) ) return a;
          goto invalid;
      }
      if ( ! expA ) {
          if ( ! sigA ) return a;
          normExpSig = softfloat_normSubnormalF64Sig( sigA );
          expA = normExpSig.exp;
          sigA = normExpSig.sig;
      }
      expZ = ( ( expA - 0x3FF )>>1 ) + 0x3FE;
      sigA |= UINT64_C( 0x0010000000000000 );
      sigZ32 = softfloat_estimateSqrt32( expA, sigA>>21 );
      sigA <<= 9 - ( expA & 1 );
      sigZ =
          softfloat_estimateDiv128To64( sigA, 0, (uint_fast64_t) sigZ32<<32 )
              + ( (uint_fast64_t) sigZ32<<30 );
      if ( ( sigZ & 0x1FF ) <= 5 ) {
          term = softfloat_mul64To128( sigZ, sigZ );
          rem = softfloat_sub128( sigA, 0, term.v64, term.v0 );
          while ( UINT64_C( 0x8000000000000000 ) <= rem.v64 ) {
              --sigZ;
              rem =
                  softfloat_add128(
                      rem.v64, rem.v0, sigZ>>63, (uint64_t) ( sigZ<<1 ) );
          }
          sigZ |= ( ( rem.v64 | rem.v0 ) != 0 );
      }
      return softfloat_roundPackToF64( 0, expZ, sigZ );
   invalid:
      softfloat_raiseFlags( softfloat_flag_invalid );
      uiZ = defaultNaNF64UI;
   uiZ:
      uZ.ui = uiZ;
      return uZ.f;
  
  }
  
  