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/*[
div.c
LOCAL CHAR SccsID[]="@(#)div.c 1.8 02/12/95";
DIV 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 <div.h>
#include <c_div64.h>
/*
=====================================================================
EXTERNAL FUNCTIONS START HERE.
=====================================================================
*/
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Unsigned Divide. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
DIV8
IFN1(
IU32, op2 /* divisor operand */
)
{
IU32 result;
IU32 op1;
if ( op2 == 0 )
Int0(); /* Divide by Zero Exception */
op1 = GET_AX();
result = op1 / op2; /* Do operation */
if ( result & 0xff00 )
Int0(); /* Result doesn't fit in destination */
SET_AL(result); /* Store Quotient */
SET_AH(op1 % op2); /* Store Remainder */
/*
* PCBench attempts to distinguish between processors by checking for
* the DIV8 instruction leaving all flags unchanged or clear. It is
* important we behave through this test in the same way as the 'real'
* 486 otherwise the app asks us to perform some unsupported ops.
*
* The real 486 has the following ('undefined') behaviour:
* CF set
* PF = pf_table[op2 - 1]
* AF = !( (op2 & 0xf) == 0 )
* ZF clear
* SF = (op2 <= 0x80)
* OF = some function of the actual division
*
* Given that the PCBench test is for a simple all-zero case, and that
* implementing the above is a needless overhead on the assembler CPU,
* we take the simplified form of ZF clear, CF set.
*/
#ifdef SET_UNDEFINED_DIV_FLAG
SET_CF(1);
SET_ZF(0);
SET_SF(UNDEFINED_FLAG);
SET_OF(UNDEFINED_FLAG);
SET_PF(UNDEFINED_FLAG);
SET_AF(UNDEFINED_FLAG);
#endif
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Unsigned Divide. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
DIV16
IFN1(
IU32, op2 /* divisor operand */
)
{
IU32 result;
IU32 op1;
if ( op2 == 0 )
Int0(); /* Divide by Zero Exception */
op1 = (IU32)GET_DX() << 16 | GET_AX();
result = op1 / op2; /* Do operation */
if ( result & 0xffff0000 )
Int0(); /* Result doesn't fit in destination */
SET_AX(result); /* Store Quotient */
SET_DX(op1 % op2); /* Store Remainder */
/* Set all undefined flag(s) */
#ifdef SET_UNDEFINED_DIV_FLAG
SET_CF(1); /* see DIV8 for flag choice reasoning */
SET_ZF(0);
SET_OF(UNDEFINED_FLAG);
SET_SF(UNDEFINED_FLAG);
SET_PF(UNDEFINED_FLAG);
SET_AF(UNDEFINED_FLAG);
#endif
}
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
/* Unsigned Divide. */
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
GLOBAL VOID
DIV32
IFN1(
IU32, op2 /* divisor operand */
)
{
IU32 lr; /* low result */
IU32 hr; /* high result */
IU32 rem; /* remainder */
if ( op2 == 0 )
Int0(); /* Divide by Zero Exception */
hr = GET_EDX();
lr = GET_EAX();
divu64(&hr, &lr, op2, &rem); /* Do operation */
if ( hr )
Int0(); /* Result doesn't fit in destination */
SET_EAX(lr); /* Store Quotient */
SET_EDX(rem); /* Store Remainder */
/* Set all undefined flag(s) */
#ifdef SET_UNDEFINED_DIV_FLAG
SET_CF(1); /* see DIV8 for flag choice reasoning */
SET_ZF(0);
SET_OF(UNDEFINED_FLAG);
SET_SF(UNDEFINED_FLAG);
SET_PF(UNDEFINED_FLAG);
SET_AF(UNDEFINED_FLAG);
#endif
}
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