102 lines
3.1 KiB
C
102 lines
3.1 KiB
C
/* $Header$ */
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/* EXPRESSION DESCRIPTOR */
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/* What we want to define is the struct expr, but since it contains
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a union of various goodies, we define them first; so be patient.
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*/
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struct value {
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struct idf *vl_idf; /* idf of an external name or 0 */
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arith vl_value; /* constant, or offset if idf != 0 */
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};
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struct string {
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char *sg_value; /* string of characters repr. the constant */
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label sg_datlab; /* global data-label */
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};
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struct floating {
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char *fl_value; /* pointer to string repr. the fp const. */
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label fl_datlab; /* global data_label */
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};
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struct oper {
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struct type *op_type; /* resulting type of the operation */
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struct expr *op_left;
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int op_oper; /* the symbol of the operator */
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struct expr *op_right;
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};
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/* The following constants indicate the class of the expression: */
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#define Value 0 /* it is a value known at load time */
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#define String 1 /* it is a string constant */
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#define Float 2 /* it is a floating point constant */
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#define Oper 3 /* it is a run-time expression */
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#define Type 4 /* only its type is relevant */
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struct expr {
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struct expr *next;
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char *ex_file; /* the file it (probably) comes from */
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unsigned int ex_line; /* the line it (probably) comes from */
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struct type *ex_type;
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char ex_lvalue;
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char ex_flags;
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int ex_class;
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int ex_depth;
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union {
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struct value ex_value;
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struct string ex_string;
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struct floating ex_float;
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struct oper ex_oper;
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} ex_object;
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};
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/* some abbreviated selections */
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#define VL_VALUE ex_object.ex_value.vl_value
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#define VL_IDF ex_object.ex_value.vl_idf
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#define SG_VALUE ex_object.ex_string.sg_value
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#define SG_DATLAB ex_object.ex_string.sg_datlab
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#define FL_VALUE ex_object.ex_float.fl_value
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#define FL_DATLAB ex_object.ex_float.fl_datlab
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#define OP_TYPE ex_object.ex_oper.op_type
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#define OP_LEFT ex_object.ex_oper.op_left
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#define OP_OPER ex_object.ex_oper.op_oper
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#define OP_RIGHT ex_object.ex_oper.op_right
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#define EXPRTYPE(e) ((e)->ex_type->tp_fund)
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/* An expression is a `load-time constant' if it is of the form
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<idf> +/- <integral> or <integral>;
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it is a `compile-time constant' if it is an <integral>.
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*/
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#define is_ld_cst(e) ((e)->ex_lvalue == 0 && (e)->ex_class == Value)
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#define is_cp_cst(e) (is_ld_cst(e) && (e)->VL_IDF == 0)
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/* a floating constant expression ?
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*/
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#define is_fp_cst(e) ((e)->ex_class == Float)
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/* some bits for the ex_flag field, to keep track of various
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interesting properties of an expression.
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*/
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#define EX_SIZEOF 001 /* contains sizeof operator */
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#define EX_CAST 002 /* contains cast */
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#define EX_LOGICAL 004 /* contains logical operator */
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#define EX_COMMA 010 /* contains expression comma */
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#define EX_PARENS 020 /* the top level is parenthesized */
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#define NILEXPR ((struct expr *)0)
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extern struct expr *intexpr(), *new_oper();
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/* allocation definitions of struct expr */
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/* ALLOCDEF "expr" */
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extern char *st_alloc();
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extern struct expr *h_expr;
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#define new_expr() ((struct expr *) \
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st_alloc((char **)&h_expr, sizeof(struct expr)))
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#define free_expr(p) st_free(p, h_expr, sizeof(struct expr))
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#define ISCOMMA(e) ((e)->ex_class == Oper && (e)->OP_OPER == INITCOMMA)
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