softfloat/s_estimateDiv128To64.c

   1
   2 #include <stdint.h>
   3 #include "platform.h"
   4 #include "primitives.h"
   5
   6 uint64_t softfloat_estimateDiv128To64( uint64_t a64, uint64_t a0, uint64_t b )
   7 {
   8     uint32_t b32;
   9     uint64_t z;
  10     struct uint128 term, rem;
  11     uint64_t rem32;
  12
  13     if ( b <= a64 ) return UINT64_C( 0xFFFFFFFFFFFFFFFF );
  14     b32 = b>>32;
  15     z = ( (uint64_t) b32<<32 <= a64 ) ? UINT64_C( 0xFFFFFFFF00000000 )
  16             : ( a64 / b32 )<<32;
  17     term = softfloat_mul64To128( b, z );
  18     rem = softfloat_sub128( a64, a0, term.v64, term.v0 );
  19     while ( UINT64_C( 0x8000000000000000 ) <= rem.v64 ) {
  20         z -= UINT64_C( 0x100000000 );
  21         rem = softfloat_add128( rem.v64, rem.v0, b32, (uint64_t) ( b<<32 ) );
  22     }
  23     rem32 = ( rem.v64<<32 ) | ( rem.v0>>32 );
  24     z |= ( (uint64_t) b32<<32 <= rem32 ) ? 0xFFFFFFFF : rem32 / b32;
  25     return z;
  26
  27 }
  28