//This is the software interrupt num
//we will use.  See Software Int's for
//picking a num.  Nums are subject to change.

#define I_F_UNARY_MINUS I_USER

asm
{

//This changes the sign of the floating
//point val in RAX
  F_UNARY_MINUS_INT::
  PUSH  RAX
  FLD   U64 [RSP]
  FCHS
  FSTP  U64 [RSP]
  POP   RAX
  IRET

//This does the same thing, but not as
//an interrupt.
  F_UNARY_MINUS_CALL::
  PUSH  RAX
  FLD   U64 [RSP]
  FCHS
  FSTP  U64 [RSP]
  POP   RAX
  RET

//This invokes the interrupt version
//with a C callable function.
  _F_UM_INT::
  PUSH  RBP
  MOV   RBP,RSP
  MOV   RAX,SF_ARG1[RBP]
  INT   I_F_UNARY_MINUS
  POP   RBP
  RET1  8

//This invokes the call version
//with a C callable function.
  _F_UM_CALL::
  PUSH  RBP
  MOV   RBP,RSP
  MOV   RAX,SF_ARG1[RBP]
  CALL  F_UNARY_MINUS_CALL
  POP   RBP
  RET1  8
}

_extern _F_UM_INT F64 UnaryMinusInt(F64 d);
_extern _F_UM_CALL F64 UnaryMinusCall(F64 d);

#define SAMPLE_SIZE     1000000
U0 TimeIns()
{
  I64 start,end;
  I64 i,old_irq;
  CPURep;
  old_irq=IntEntrySet(I_F_UNARY_MINUS,F_UNARY_MINUS_INT,IDTET_TRAP);
  //Measure interrupt time
  start=GetTSC;
  for (i=0; i<SAMPLE_SIZE; i++)
    UnaryMinusInt(pi);
  end=GetTSC;
  "Interrupt Cycles: %10.5f\n"
  ,ToF64(end-start)/SAMPLE_SIZE;
  //Measure call time
  start=GetTSC;
  for (i=0; i<SAMPLE_SIZE; i++)
    UnaryMinusCall(pi);
  end=GetTSC;
  "Call      Cycles: %10.5f\n"
  ,ToF64(end-start)/SAMPLE_SIZE;
  IntEntrySet(I_F_UNARY_MINUS,old_irq,IDTET_IRQ);
}

TimeIns;

/*  Program Output
6 Cores 3.395GHz
Interrupt Cycles:  573.98543
Call      Cycles:    9.74349
*/