fcsel.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 132 行

/****************************************************************************
*
*                            Open Watcom Project
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*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
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*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
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*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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* Description:  WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
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//
// FCSEL  : Select statement F-Code processor
//

#include "ftnstd.h"
#include "symbol.h"
#include "cgdefs.h"
#include "cg.h"
#include "fcodes.h"
#include "emitobj.h"

//=================== Back End Code Generation Routines ====================

extern  void            CGSelect(sel_handle,cg_name);
extern  sel_handle      CGSelInit( void );
extern  void            CGSelOther(sel_handle,label_handle);
extern  void            CGSelRange(sel_handle,signed_32,signed_32,label_handle);
extern  cg_name         CGUnary(cg_op,cg_name,cg_type);

//=========================================================================

extern  label_handle    GetLabel(int);
extern  label_handle    GetStmtLabel(sym_id);
extern  void            RefStmtLabel(sym_id);
extern  cg_name         SymValue(sym_id);
extern  cg_name         SymAddr(sym_id);
extern  cg_name         SCBPointer(cg_name);


void    DoSelect( FCODE kind ) {
//==============================

// Select processing for SELECT and computed GOTO.

    sel_handle          s;
    int                 cases;
    int                 stmts;
    label_handle        label;
    sym_id              sn;
    sym_id              sel_sym;
    cg_name             sel_expr;
    obj_ptr             curr_obj;
    signed_32           lo;
    signed_32           hi;

    s = CGSelInit();
    cases = GetU16();
    stmts = cases;
    CGSelOther( s, GetLabel( GetU16() ) );
    curr_obj = FCodeTell( 0 );
    while( cases != 0 ) {
        if( kind == FC_COMPUTED_GOTO ) {
            sn = GetPtr();
            label = GetStmtLabel( sn );
        } else {
            label = GetLabel( GetU16() );
        }
        hi = GetConst32();
        lo = GetConst32();
        // the following code is to get around a bug
        // in the code generator - eventually the "if"
        // block should be replaced by the "else" block
        if( (hi ^ lo) < 0 ) {
            CGSelRange( s, lo, -1, label );
            CGSelRange( s, 0, hi, label );
        } else {
            CGSelRange( s, lo, hi, label );
        }
        --cases;
    }
    sel_sym = GetPtr();
    if( sel_sym->ns.typ == TY_CHAR ) {
        sel_expr = CGUnary( O_POINTS,
                            SCBPointer( SymAddr( sel_sym ) ),
                            T_UINT_1 );
    } else {
        sel_expr = SymValue( sel_sym );
    }
    CGSelect( s, sel_expr );
    if( kind == FC_COMPUTED_GOTO ) {
        FCodeSeek( curr_obj );
        while( stmts != 0 ) {
            RefStmtLabel( GetPtr() );
            GetConst32();
            GetConst32();
            --stmts;
        }
        GetPtr(); // skip select variable
    }
}


void    FCSelect( void ) {
//========================

// Perform SELECT statement.

    DoSelect( FC_SELECT );
}