Result bvSignExtendBothWays(vector<FixedBits*>& children, FixedBits& output)
{
assert(children.size() == 2);
// The second argument is a junk size arugment.
FixedBits& input = *children[0];
const int inputBitWidth = input.getWidth();
const int outputBitWidth = output.getWidth();
assert(inputBitWidth <= outputBitWidth);
Result result = makeEqual(input, output, 0, inputBitWidth);
if (CONFLICT == result)
return CONFLICT;
// If any of the topmost bits of the output are fixed. Then they all should
// be.
// They should all be fixed to the same value.
bool found = false;
bool setTo;
for (int i = inputBitWidth - /**/ 1 /**/; i < outputBitWidth; i++)
{
if (output.isFixed(i))
{
setTo = output.getValue(i);
found = true;
break;
}
}
if (found)
{
for (int i = inputBitWidth - 1; i < outputBitWidth; i++)
{
if (output.isFixed(i) && (output.getValue(i) != setTo))
return CONFLICT; // if any are set to the wrong value! bad.
else if (!output.isFixed(i))
{
output.setFixed(i, true);
output.setValue(i, setTo);
result = CHANGED;
}
}
Result result2 = makeEqual(input, output, 0, inputBitWidth);
if (CONFLICT == result2)
return CONFLICT;
}
return result;
}
Result bvZeroExtendBothWays(vector<FixedBits*>& children, FixedBits& output)
{
assert(children.size() == 2);
// The second argument is a junk size arugment.
FixedBits& input = *children[0];
const int inputBitWidth = input.getWidth();
const int outputBitWidth = output.getWidth();
Result result = makeEqual(input, output, 0, inputBitWidth);
if (CONFLICT == result)
return CONFLICT;
// Fix all the topmost bits of the output to zero.
for (int i = inputBitWidth; i < outputBitWidth; i++)
{
if (output.isFixed(i) && output.getValue(i))
return CONFLICT; // set to one. Never right.
else if (!output.isFixed(i))
{
output.setFixed(i, true);
output.setValue(i, false);
result = CHANGED;
}
}
return result;
}
// If the guard is fixed, make equal the appropriate input and output.
// If one input can not possibly be the output. Then set the guard to make it
// the other one.
// If both values are the same. Set the output to that value.
Result bvITEBothWays(vector<FixedBits*>& children, FixedBits& output)
{
Result result = NO_CHANGE;
assert(3 == children.size());
const int bitWidth = output.getWidth();
FixedBits& guard = *children[0];
FixedBits& c1 = *children[1];
FixedBits& c2 = *children[2];
assert(c1.getWidth() == c2.getWidth());
assert(output.getWidth() == c2.getWidth());
if (guard.isFixed(0) && guard.getValue(0))
{ // guard fixed to true. So make (first arg == output)
result = makeEqual(output, c1, 0, bitWidth);
if (CONFLICT == result)
return CONFLICT;
}
else if (guard.isFixed(0) && !guard.getValue(0))
{
result = makeEqual(output, c2, 0, bitWidth);
if (CONFLICT == result)
return CONFLICT;
}
else
{
for (int i = 0; i < bitWidth; i++)
{
if (c1.isFixed(i) && c2.isFixed(i) && (c1.getValue(i) == c2.getValue(i)))
{
if (output.isFixed(i) && (output.getValue(i) != c1.getValue(i)))
return CONFLICT;
if (!output.isFixed(i))
{
output.setFixed(i, true);
output.setValue(i, c1.getValue(i));
result = CHANGED;
}
}
}
}
bool changed = false;
if (CHANGED == result)
changed = true;
for (int i = 0; i < bitWidth; i++)
{
if (output.isFixed(i))
{
if (c1.isFixed(i) && (c1.getValue(i) != output.getValue(i)))
{
// c1 is fixed to a value that's not the same as the output.
if (!guard.isFixed(0))
{
guard.setFixed(0, true);
guard.setValue(0, false);
result = bvITEBothWays(children, output);
if (CONFLICT == result)
return CONFLICT;
changed = true;
}
else if (guard.getValue(0))
return CONFLICT;
}
if (c2.isFixed(i) && (c2.getValue(i) != output.getValue(i)))
{
// c2 is fixed to a value that's not the same as the output.
if (!guard.isFixed(0))
{
guard.setFixed(0, true);
guard.setValue(0, true);
result = bvITEBothWays(children, output);
if (CONFLICT == result)
return CONFLICT;
changed = true;
}
else if (!guard.getValue(0))
return CONFLICT;
}
}
}
if (result == CONFLICT)
return CONFLICT;
if (changed)
return CHANGED;
return result;
}
/** Parse with one token worth of look-ahead, return the expression object representing
the syntax parsed.
@param tok next token from the input.
@param fp file subsequent tokens are being read from.
@return the expression object constructed from the input.
*/
Expr *parse( char *tok, FILE *fp )
{
// Create a literal token for anything that looks like a number.
{
long dummy;
int pos;
// See if the whole token parses as a long int.
if ( sscanf( tok, "%ld%n", &dummy, &pos ) == 1 &&
pos == strlen( tok ) ) {
// Copy the literal to a dynamically allocated string, since makeLiteral wants
// a string it can keep.
char *str = (char *) malloc( strlen( tok ) + 1 );
return makeLiteral( strcpy( str, tok ) );
}
}
// Create a literal token for a quoted string, without the quotes.
if ( tok[ 0 ] == '"' ) {
// Same as above, make a dynamically allocated copy of the token that the literal
// expression can keep as long as at wants to.
int len = strlen( tok );
char *str = (char *) malloc( len - 1 );
strncpy( str, tok + 1, len - 2 );
str[ len - 2 ] = '\0';
return makeLiteral( str );
}
// Handle compound statements
if ( strcmp( tok, "{" ) == 0 ) {
int len = 0;
int cap = INITIAL_CAPACITY;
Expr **eList = (Expr **) malloc( cap * sizeof( Expr * ) );
// Keep parsing subexpressions until we hit the closing curly bracket.
while ( strcmp( expectToken( tok, fp ), "}" ) != 0 ) {
if ( len >= cap )
eList = (Expr **) realloc( eList, ( cap *= 2 ) * sizeof( Expr * ) );
eList[ len++ ] = parse( tok, fp );
}
return makeCompound( eList, len );
}
// Handle language operators (reserved words)
if ( strcmp( tok, "print" ) == 0 ) {
// Parse the one argument to print, and create a print expression.
Expr *arg = parse( expectToken( tok, fp ), fp );
return makePrint( arg );
}
if ( strcmp( tok, "set" ) == 0 ) {
// Parse the two operands, then make a set expression with them.
char *str = expectToken( tok, fp );
int len = strlen( str );
char *name = (char *) malloc( len + 1 );
strcpy( name, str );
name[ len ] = '\0';
if ( !isalpha(name[0]) || strlen( name ) > MAX_VAR || strchr( name, LEFT_BRACKET ) || strchr( name, RIGHT_BRACKET ) || strchr( name, POUND ) ) {
// Complain if we can't make sense of the variable.
fprintf( stderr, "line %d: invalid variable name \"%s\"\n", linesRead(), name );
exit( EXIT_FAILURE );
}
Expr *expr = parse( expectToken( tok, fp ), fp );
Expr *set = makeSet
( name, expr );
free(name);
return set;
}
if ( strcmp( tok, "add" ) == 0 ) {
// Parse the two operands, then make an add expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeAdd( op1, op2 );
}
if ( strcmp( tok, "sub" ) == 0 ) {
// Parse the two operands, then make a sub expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeSub( op1, op2 );
}
if ( strcmp( tok, "mul" ) == 0 ) {
// Parse the two operands, then make a mul expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeMul( op1, op2 );
}
if ( strcmp( tok, "div" ) == 0 ) {
// Parse the two operands, then make a div expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeDiv
( op1, op2 );
}
if ( strcmp( tok, "equal" ) == 0 ) {
// Parse the two operands, then make an equal expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeEqual
( op1, op2 );
}
if ( strcmp( tok, "less" ) == 0 ) {
// Parse the two operands, then make a less expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeLess
( op1, op2 );
}
if ( strcmp( tok, "not" ) == 0 ) {
// Parse the operand, then make a not expression with it.
Expr *op = parse( expectToken( tok, fp ), fp );
return makeNot
( op );
}
if ( strcmp( tok, "and" ) == 0 ) {
// Parse the two operands, then make an and expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeAnd
( op1, op2 );
}
if ( strcmp( tok, "or" ) == 0 ) {
// Parse the two operands, then make an or expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeOr
( op1, op2 );
}
if ( strcmp( tok, "if" ) == 0 ) {
// Parse the two operands, then make an if expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeIf
( op1, op2 );
}
if ( strcmp( tok, "while" ) == 0 ) {
// Parse the two operands, then make a while expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeWhile
( op1, op2 );
}
if ( strcmp( tok, "concat" ) == 0 ) {
// Parse the two operands, then make a concatenation expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
return makeConcat
( op1, op2 );
}
if ( strcmp( tok, "substr" ) == 0 ) {
// Parse the three operands, then make a substring expression with them.
Expr *op1 = parse( expectToken( tok, fp ), fp );
Expr *op2 = parse( expectToken( tok, fp ), fp );
Expr *op3 = parse( expectToken( tok, fp ), fp );
return makeSubstr
( op1, op2, op3 );
}
// Handle variables
if ( isalpha(tok[0]) && strlen( tok ) <= MAX_VAR && !strchr( tok, LEFT_BRACKET ) && !strchr( tok, RIGHT_BRACKET ) && !strchr( tok, POUND ) ) {
// Parse the variable name and make a variable expression.
char *str = tok;
int len = strlen( str );
char *name = (char *) malloc( len + 1 );
strcpy( name, str );
name[ len ] = '\0';
Expr *var = makeVariable( name );
free(name);
return var;
}
// Complain if we can't make sense of the token.
fprintf( stderr, "line %d: invalid token \"%s\"\n", linesRead(), tok );
exit( EXIT_FAILURE );
// Never reached.
return NULL;
}
