state_t __2DROP(context_t *ctx)
{
int x1, x2;
if (popnum(ctx->ds, &x2) && popnum(ctx->ds, &x1))
{
return OK;
}
else
{
return stack_underflow(ctx);
}
}
state_t __SWAP(context_t *ctx)
{
int x1, x2;
if (popnum(ctx->ds, &x2) && popnum(ctx->ds, &x1))
{
pushnum(ctx->ds, x2);
pushnum(ctx->ds, x1);
return OK;
}
else
{
return stack_underflow(ctx);
}
}
state_t __2OVER(context_t *ctx)
{
int x1, x2, x3, x4;
if (popnum(ctx->ds, &x4) && popnum(ctx->ds, &x3) && popnum(ctx->ds, &x2) && popnum(ctx->ds, &x1))
{
pushnum(ctx->ds, x1);
pushnum(ctx->ds, x2);
pushnum(ctx->ds, x3);
pushnum(ctx->ds, x4);
pushnum(ctx->ds, x1);
pushnum(ctx->ds, x2);
return OK;
}
else
{
return stack_underflow(ctx);
}
}
state_t __DROP(context_t *ctx)
{
int x;
if (popnum(ctx->ds, &x))
{
return OK;
}
else
{
return stack_underflow(ctx);
}
}
state_t __RDROP(context_t *ctx)
{
int x;
if (popnum(ctx->rs, &x))
{
return OK;
}
else
{
return error(ctx, -6); // return stack underflow
}
}
state_t __RFROM(context_t *ctx)
{
int x1;
if (popnum(ctx->rs, &x1))
{
pushnum(ctx->ds, x1);
return OK;
}
else
{
return error(ctx, -6); // return stack underflow
}
}
state_t __TOR(context_t *ctx)
{
int x1;
if (popnum(ctx->ds, &x1))
{
pushnum(ctx->rs, x1);
return OK;
}
else
{
return stack_underflow(ctx);
}
}
/*
** VALOF -- compute value of expression
**
** This is the real expression processor. It handles sequencing
** and precedence.
**
** Parameters:
** terminator -- the symbol which should terminate
** the expression.
**
** Returns:
** The value of the expression.
**
** Side Effects:
** Gobbles input.
**
** Requires:
** exprfind -- to read operands.
** opfind -- to read operators.
** exp_op -- to perform operations.
**
** Called By:
** expr
**
** Diagnostics:
** Extra Parenthesis found: assumed typo
** An unmatched right parenthesis was read.
** It was thrown away.
** Insufficient parenthesis found: assumed zero.
** An unmatched left parenthesis was left
** in the operator stack at the end of the
** expression. The value zero was taken
** for the expression.
**
** Syserrs:
** none
*/
int
valof(int terminator)
{
register int number;
register int operator;
pushop(SEPERATOR); /* initialize the stack */
for(;;) {
number = exprfind();
if (ExprError)
return(0);
operator = opfind();
if (ExprError)
return(0);
if (operator == RIGHTP || operator == END)
break;
/* Do all previous operations with a higher precedence */
while (ExprPrec[operator] <= ExprPrec[ExprOptr[-1]])
number = exp_op(popop(), popnum(), number);
pushop(operator);
pushnum(number);
}
if (operator != terminator) /* ExprError in operators */
if (operator == RIGHTP)
printf("Extra parenthesis found: assumed typo.\n");
else {
ExprError = TRUE;
printf("Insufficient parenthesis found: Assumed zero.\n");
return(0);
}
/* Empty stack for this call of valof */
while ((operator = popop()) != SEPERATOR)
number = exp_op(operator, popnum(), number);
return(number);
}
state_t __PICK(context_t *ctx)
{
int u;
if (popnum(ctx->ds, &u))
{
dlist_elem_t *element = dlist_head(ctx->ds);
while (u >= 0 && element != NULL)
{
if (u == 0)
{
int *num = dlist_data(element);
pushnum(ctx->ds, *num);
return OK;
}
u--;
element = dlist_next(element);
}
}
return error(ctx, -11); // result out of range
}
