blob: 02671a6bb9712b4b7857f9dc31f0d2dbab08156b (
plain) (
tree)
|
|
/*[
neg.c
LOCAL CHAR SccsID[]="@(#)neg.c 1.5 02/09/94";
NEG CPU functions.
------------------
]*/
#include <insignia.h>
#include <host_def.h>
#include <xt.h>
#include <c_main.h>
#include <c_addr.h>
#include <c_bsic.h>
#include <c_prot.h>
#include <c_seg.h>
#include <c_stack.h>
#include <c_xcptn.h>
#include <c_reg.h>
#include <neg.h>
/*
=====================================================================
EXTERNAL FUNCTIONS START HERE.
=====================================================================
*/
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Generic - one size fits all 'neg'. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
NEG
IFN2(
IU32 *, pop1, /* pntr to dst/src operand */
IUM8, op_sz /* 8, 16 or 32-bit */
)
{
IU32 result;
IU32 msb;
IU32 op1_msb;
IU32 res_msb;
msb = SZ2MSB(op_sz);
result = -(*pop1) & SZ2MASK(op_sz); /* Do operation */
op1_msb = (*pop1 & msb) != 0; /* Isolate all msb's */
res_msb = (result & msb) != 0;
/* Determine flags */
SET_OF(op1_msb & res_msb); /* OF = op1 & res */
SET_CF(op1_msb | res_msb); /* CF = op1 | res */
SET_PF(pf_table[result & BYTE_MASK]);
SET_ZF(result == 0);
SET_SF((result & msb) != 0); /* SF = MSB */
SET_AF(((*pop1 ^ result) & BIT4_MASK) != 0); /* AF = Bit 4 carry */
*pop1 = result; /* Return answer */
}
|
