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/* SPDX-License-Identifier: BSD-2-Clause */
/* Copyright 1996-2017 The NASM Authors - All Rights Reserved */
/*
* exprlib.c
*
* Library routines to manipulate expression data types.
*/
#include "nasm.h"
/*
* Return true if the argument is a simple scalar. (Or a far-
* absolute, which counts.)
*/
bool is_simple(const expr *vect)
{
while (vect->type && !vect->value)
vect++;
if (!vect->type)
return true;
if (vect->type != EXPR_SIMPLE)
return false;
do {
vect++;
} while (vect->type && !vect->value);
if (vect->type && vect->type < EXPR_SEGBASE + SEG_ABS)
return false;
return true;
}
/*
* Return true if the argument is a simple scalar, _NOT_ a far-
* absolute.
*/
bool is_really_simple(const expr *vect)
{
while (vect->type && !vect->value)
vect++;
if (!vect->type)
return true;
if (vect->type != EXPR_SIMPLE)
return false;
do {
vect++;
} while (vect->type && !vect->value);
if (vect->type)
return false;
return true;
}
/*
* Classify an expression based on its components
*/
enum expr_classes expr_class(const expr *vect)
{
enum expr_classes class = EC_ZERO;
for (; vect->type; vect++) {
if (!vect->value) {
/* Value-0 term */
} else if (vect->type < EXPR_UNKNOWN) {
if ((class & EC_REGISTER) || vect->value != 1)
class |= EC_REGEXPR;
else
class |= EC_REGISTER;
} else if (vect->type == EXPR_UNKNOWN) {
class |= EC_UNKNOWN;
} else if (vect->type == EXPR_SIMPLE) {
/* Pure number term */
class |= EC_CONST;
} else if (vect->type == EXPR_WRT) {
class |= EC_WRT;
} else if (vect->type < EXPR_SEGBASE) {
class |= EC_COMPLEX;
} else if (vect->type >= EXPR_SEGBASE + SEG_ABS) {
/* It is an absolute segment */
if (class & (EC_SEG|EC_SEGABS))
class |= EC_COMPLEX;
class |= EC_SEGABS;
} else {
/* It is a segment */
if (vect->value == 1) {
if (class & (EC_SEG|EC_SEGABS))
class |= EC_COMPLEX;
class |= EC_SEG;
} else if (vect->value == -1) {
/* can only subtract current segment, and only once */
if (vect->type != location.segment + EXPR_SEGBASE ||
(class & EC_SELFREL))
class |= EC_COMPLEX;
class |= EC_SELFREL;
} else {
/* Non-simple segment arithmetic */
class |= EC_COMPLEX;
}
}
}
return class;
}
/*
* Return true if the argument is relocatable (i.e. a simple
* scalar, plus at most one segment-base, possibly a subtraction
* of the current segment base, plus possibly a WRT).
*/
bool is_reloc(const expr *vect)
{
return !(expr_class(vect) & ~EC_RELOC);
}
/*
* Return true if the argument contains an `unknown' part.
*/
bool is_unknown(const expr *vect)
{
return !!(expr_class(vect) & EC_UNKNOWN);
}
/*
* Return true if the argument contains nothing but an `unknown'
* part.
*/
bool is_just_unknown(const expr *vect)
{
return expr_class(vect) == EC_UNKNOWN;
}
/*
* Return the scalar part of a relocatable vector. (Including
* simple scalar vectors - those qualify as relocatable.)
*/
int64_t reloc_value(const expr *vect)
{
while (vect->type && !vect->value)
vect++;
if (!vect->type)
return 0;
if (vect->type == EXPR_SIMPLE)
return vect->value;
else
return 0;
}
/*
* Return the segment number of a relocatable vector, or NO_SEG for
* simple scalars.
*/
int32_t reloc_seg(const expr *vect)
{
for (; vect->type; vect++) {
if (vect->type >= EXPR_SEGBASE && vect->value == 1)
return vect->type - EXPR_SEGBASE;
}
return NO_SEG;
}
/*
* Return the WRT segment number of a relocatable vector, or NO_SEG
* if no WRT part is present.
*/
int32_t reloc_wrt(const expr *vect)
{
while (vect->type && vect->type < EXPR_WRT)
vect++;
if (vect->type == EXPR_WRT) {
return vect->value;
} else
return NO_SEG;
}
/*
* Return true if this expression contains a subtraction of the location
*/
bool is_self_relative(const expr *vect)
{
return !!(expr_class(vect) & EC_SELFREL);
}
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