FPREG

Coprocessor stack register element.

typedef struct _FPREG {
  ULONG      losig;    /*  Low 32-bits of the significand. */
  ULONG      hisig;    /*  High 32-bits of the significand. */
  USHORT     signexp;  /*  Sign and exponent. */
} FPREG;

typedef   FPREG   * PFPREG ;

A floating point register is 80 bits wide and consists of three fields. The following graphic shows the layout of the floating point register:

  79  78         64 63                                     0
  ┌───┬────────────┬───────────────────────────────────────┐
  │   │            │             Significand               │
  └─┬─┴──────┬─────┴───────────────────────────────────────┘
    │        │
    │        Exponent
   Sign