/*
HEADER:     ;
TITLE:      Frankenstein Cross Assemblers;
VERSION:    2.0;
DESCRIPTION: "  Reconfigurable Cross-assembler producing Intel (TM)
        Hex format object records.  ";
SYSTEM:     UNIX, MS-Dos ;
FILENAME:   frapsub.c ;
WARNINGS:   "This software is in the public domain.  
        Any prior copyright claims are relinquished.  

        This software is distributed with no warranty whatever.  
        The author takes no responsibility for the consequences 
        of its use.  "  ;
SEE-ALSO:   frasmain.c;
AUTHORS:    Mark Zenier;
*/

/*
    description Parser phase utility routines
    History     September 1987
            September 14, 1990 Dosify, 6 char unique names
*/

#include "config.h"
#include "file/file.h"
#include "fragcon.h"
#include <stdio.h>
#include <stdlib.h>
#include "frasmdat.h"
#include "types.h"
#include "protos.h"
#include "intermed.h"
#include "memo_string.h"

#define STRALLOCSZ 4096

#if 0
    local char *currstr;

char *savestring(const char *stx, int len)
/*
    description save a character string in permanent (interpass) memory
    parameters  the string and its length
    globals     the string pool
    return      a pointer to the saved string
*/
{
    char * rv;
    static int savestrleft = 0;
    size_t allocsz = len + 1 < STRALLOCSZ ? STRALLOCSZ : len + 1;

    if (savestrleft < (len + 1))
    {
        if((currstr = (char *)malloc(allocsz)) == (char *)NULL)
        {
            frafatal("cannot allocate string storage");
        }
        savestrleft = allocsz;
    }

    savestrleft -= (len+1);

    rv = currstr;
    for(; len > 0; len--)
        *currstr++ = *stx++;
    *currstr++ = '\0';

    return rv;
}
#endif

/* expression node operations */

/* expression tree element */
struct etelem
{
    int evs;
    int op;
    int left, right;
    int val;
    struct symel *sym;
};

#define NUMENODE INBUFFSZ
struct etelem enode[NUMENODE];

local int nextenode = 1;

/* non general, one exprlist or stringlist per line */
int nextexprs = 0;
int nextstrs = 0;

void clrexpr(void)
/*
    description clear out the stuff used for each line
            the temporary string pool
            the expression tree storage pool
            the string and expression lists
*/
{
    nextenode = 1;
    nextexprs = nextstrs = 0;
}

int exprnode(int swact, int left, int op, int right, int value, 
             struct symel *symbol)
/*
    description add an element to the expression tree pool
    parameters  swact, the action performed by the switch in
                the polish conversion routine, the category
                of the expression node.
            left, right  the subscripts of the decendent nodes
                    of the expression tree element
            op, the operation to preform
            value, a constant value (maybe)
            symbol, a pointer to a symbol element (maybe)
    globals     the next available table element
    return      the subscript of the expression node
*/
{
    if(nextenode >= NUMENODE)
    {
        frafatal("excessive number of subexpressions");
    }

    enode [nextenode].evs = swact;
    enode [nextenode].left = left;
    enode [nextenode].op = op;
    enode [nextenode].right = right;
    enode [nextenode].val = value;
    enode [nextenode].sym = symbol;

    return nextenode ++;
}

int nextsymnum = 1;

local struct symel *syallob;
#define SYELPB 512
local int nxtsyel = SYELPB;

struct symel *allocsym(void)
/*
    description allocate a symbol table element, and allocate
            a block if the current one is empty.  A fatal
            error if no more space can be gotten
    globals     the pointer to the current symbol table block
            the count of elements used in the block
    return      a pointer to the symbol table element
*/
{

    if(nxtsyel >= SYELPB)
    {
        if( (syallob = (struct symel *)calloc(
            SYELPB , sizeof(struct symel)))
         == (struct symel *)NULL)
        {
            frafatal("cannot allocate symbol space");
        }

        nxtsyel = 0;
    }

    return &syallob[nxtsyel++];
}


#define SYHASHOFF 13
#define SYHASHSZ 1023

int syhash(const char *str)
/*
    description produce a hash index from a character string for
            the symbol table.
    parameters  a character string
    return      an integer related in some way to the character string
*/
{
    unsigned rv = 0;
    int offset = 1;
    int c;

    while((c = *(str++)) > 0)
    {
        rv += (c - ' ') * offset;
        offset *= SYHASHOFF;
    }

    return rv % SYHASHSZ;
}

local struct symel * (shashtab[SYHASHSZ]);

static struct symel *getsymslot(const char *str)
/*
    description find an existing symbol in the symbol table, or
            allocate an new element if the symbol doen't exist.
            action: hash the string
                if there are no symbols for the hash value
                    create one for this string
                otherwise
                scan the linked list until the symbol is 
                found or the end of the list is found
                if the symbol was found
                    exit
                if the symbol was not found, allocate and
                add at the end of the linked list
                fill out the symbol
    parameters  the character string 
    globals     all the symbol table
    return      a pointer to the symbol table element for this
            character string
*/
{
    struct symel *currel, *prevel;
    int hv;

    if( (currel = shashtab[hv = syhash(str)])
        == (struct symel *)NULL)
    {
        shashtab[hv] = currel = allocsym();
    }
    else
    {
        do  {
            if(strcmp(currel->symstr, str) == 0)
            {
                return currel;
            }
            else
            {
                prevel = currel;
                currel = currel->nextsym;
            }
        } while( currel != (struct symel *)NULL);

        prevel->nextsym = currel = allocsym();
    }

    currel->symstr  = memoize_string(str); //savestring(str, strlen(str));
    currel->nextsym = (struct symel *)NULL;
    currel->tok     = 0;
    currel->value   = 0;
    currel->seg     = SSG_UNUSED;

    return currel;
}

char *currmode = "";
char *proc = NULL;
int   proc_len = 0;

struct symel *symbentryidx(const char *str, int toktyp, int hasidx, 
                           unsigned idx)
/*
    description find or add a nonreserved symbol to the symbol table
    parameters  the character string
            the syntactic token type for this charcter string
                (this is a parameter so the routine doesn't
                have to be recompiled since the yacc grammer
                provides the value)
    globals     the symbol table in all its messy glory
    return      a pointer to the symbol table element
*/
{
    struct symel * rv;
    static char *rstr = NULL;
    static int  buf_len = 0;

    if (proc && str[0] == '@' && str[1] == '@')
    {
        /* One of the '@' accounts for NUL at end... hacky. */
        /* We'll add +1 anyway. */
        int need = proc_len + strlen(str) + 1;  

        if (buf_len < need)
        {
            rstr = (char *)realloc(rstr, need * 2);
            buf_len = need * 2;
        }

        if (!rstr)
            fraerror("Out of memory.  Buy more.");

        strcpy(rstr, proc);
        rstr[proc_len] = '.';
        strcpy(rstr + proc_len + 1, str + 2);
    } else
    {
        int need = strlen(str) + 1;

        if (buf_len < need)
        {
            rstr = (char *)realloc(rstr, need * 2);
            buf_len = need * 2;
        }

        if (!rstr)
            fraerror("Out of memory.  Buy more.");

        strcpy(rstr, str);
    }

    if (hasidx)
    {
        int rstr_len = strlen(rstr);
        int need = rstr_len + 7;

        if (buf_len < need)
        {
            rstr = (char *)realloc(rstr, need * 2);
            buf_len = need * 2;
        }

        if (!rstr)
            fraerror("Out of memory.  Buy more.");

        rstr[rstr_len + 0] = 0x01;  /* divider between index and symbol */
        rstr[rstr_len + 1] = 0x80 | ((idx >>  0) & 0x7F);
        rstr[rstr_len + 2] = 0x80 | ((idx >>  7) & 0x7F);
        rstr[rstr_len + 3] = 0x80 | ((idx >> 14) & 0x7F);
        rstr[rstr_len + 4] = 0x80 | ((idx >> 21) & 0x7F);
        rstr[rstr_len + 5] = 0x80 | ((idx >> 28) & 0x0F);
        rstr[rstr_len + 6] = 0;
    }

    rv = getsymslot(rstr);

    if(rv->seg == SSG_UNUSED)
    {
        rv->tok    = toktyp;
        rv->symnum = nextsymnum++;
        rv->seg    = SSG_UNDEF;
        rv->flags  = SFLAG_NONE;
    } 

    return rv;
}

struct symel *symbentry(const char *str, int toktyp)
{
    return symbentryidx(str, toktyp, 0, 0);
}


void reservedsym(const char *str, int tok, int value)
/*
    description add a reserved symbol to the symbol table.
    parameters  the character string, must be a constant as
            the symbol table does not copy it, only point to it.
            The syntactic token value.
            The associated value of the symbol.
*/
{
    struct symel * tv;

    tv = getsymslot(str);

    if(tv->seg != SSG_UNUSED)
    {
        frafatal("cannot redefine reserved symbol");
    }

    tv->symnum = 0;
    tv->tok = tok;
    tv->seg = SSG_RESV;
    tv->value = value;

}

void buildsymbolindex(void )
/*
    description allocate and fill an array that points to each
            nonreserved symbol table element, used to reference
            the symbols in the intermediate file, in the output
            pass.
    globals     the symbol table
*/
{
    int hi;
    struct symel *curr;

    if((symbindex = (struct symel **)calloc((unsigned)nextsymnum, 
            sizeof (struct symel *))) == (struct symel **)NULL)
    {
        frafatal(" unable to allocate symbol index");
    }

    for(hi = 0; hi < SYHASHSZ; hi++)
    {
        if( (curr = shashtab[hi]) != SYMNULL)
        {
            do  {
                if( curr->symnum)
                    symbindex[curr->symnum] = curr;

                curr = curr->nextsym;
            }  while(curr != SYMNULL);
        }
    }
}

/* opcode symbol table */

#define OPHASHOFF 13
#define OPHASHSZ 1023

local int ohashtab[OPHASHSZ];

void setophash(void)
/*
    description set up the linked list hash table for the
            opcode symbols 
    globals     the opcode hash table
            the opcode table
*/
{
    int opn, pl, hv;

        /* optab[0] is reserved for the "invalid" entry */
        /*  opcode subscripts range from 0 to numopcode - 1 */
    for(opn = 1; opn < gnumopcode; opn++)
    {
        hv = opcodehash(optab[opn].opstr);

        if( (pl = ohashtab[hv]) == 0)
        {
            ohashtab[hv] = opn;
        }
        else
        {
            while( ophashlnk[pl] != 0)
            {
                pl = ophashlnk[pl];
            }

            ophashlnk[pl] = opn;
            ophashlnk[opn] = 0;
        }
    }
}


int findop(char *str)
/*
    description find an opcode table subscript
    parameters  the character string
    globals     the opcode hash linked list table
            the opcode table
    return      0 if not found
            the subscript of the matching element if found
*/
{
    int ts;

    if( (ts = ohashtab[opcodehash(str)]) == 0)
    {
        return 0;
    }

    do  {
        if(strcmp(str,optab[ts].opstr) == 0)
        {
            return ts;
        }
        else
        {
            ts = ophashlnk[ts];
        }
    } while (ts != 0);

    return 0;
}


int opcodehash(const char *str)
/*
    description hash a character string
    return      an integer related somehow to the character string
*/
{
    unsigned rv = 0;
    int offset = 1, c;

    while((c = *(str++)) > 0)
    {
        rv += (c - ' ') * offset;
        offset *= OPHASHOFF;
    }

    return rv % OPHASHSZ;
}


const char *findgen(int op, int syntax, int crit)
/*
    description given the subscript of the opcode table element,
            find the instruction generation string for the
            opcode with the given syntax and fitting the
            given criteria.  This implement a sparse matrix
            for  the dimensions [opcode, syntax] and then
            points to a list of generation elements that
            are matched to the criteria (binary set) that
            are provided by the action in the grammer for that
            specific syntax.
    parameters  Opcode table subscript
                note 0 is the value which points to an
                syntax list that will accept anything
                and gives the invalid instruction error
            Syntax, a selector, a set member
            Criteria, a integer used a a group of bit sets
    globals     the opcode table, the opcode syntax table, the
            instruction generation table
    return      a pointer to a character string, either a
            error message, or the generation string for the
            instruction
*/
{
    int sys = optab[op].subsyn, stc, gsub = 0, dctr;

    for(stc = optab[op].numsyn; stc > 0; stc--)
    {
        if( (ostab[sys].syntaxgrp & syntax) != 0)
        {
            gsub = ostab[sys].gentabsub;
            break;
        }
        else
            sys++;
    }

    if(gsub == 0)
        return ignosyn;

    for(dctr = ostab[sys].elcnt; dctr > 0; dctr--)
    {
        if( (igtab[gsub].selmask & crit) == igtab[gsub].criteria)
        {
            return igtab[gsub].genstr;
        }
        else
        {
            gsub++;
        }
    }

    return ignosel;
}

#define GSTR_PASS 0
#define GSTR_PROCESS 1

local char *goutptr; 
local char *goutbuff = NULL;
local int   gout_bs  = 0;

void goutch(char ch)
/*
    description put a character in the intermediate file buffer
            for 'D' data records
    globals     the buffer, its current position pointer
*/
{
    if (goutptr - goutbuff >= gout_bs)
    {
        gout_bs  = gout_bs << 2;
        goutbuff = (char *)realloc(goutbuff, gout_bs);
    }

    *goutptr++ = ch;
}


void gout2hex(int inv)
/*
    description output to the 'D' buffer, a byte in ascii hexadecimal
*/
{
    goutch(hexch( inv>>4 ));
    goutch(hexch( inv ));
}


void goutxnum(unsigned int num)
/*
    description output to the 'D' record buffer a long integer in
            hexadecimal
*/
{
    if(num > 15)
        goutxnum(num>>4);
    goutch(hexch((int) num ));
}


int geninstr(const char *str)
/*
    description Process an instruction generation string, from
            the parser, into a polish form expression line
            in a 'D' record in the intermediate file, after
            merging in the expression results.
    parameters  the instruction generation string
    globals     the evaluation results 
                evalr[].value   a numeric value known at
                        the time of the first pass
                evalr[].exprstr  a polish form expression
                        derived from the expression
                        parse tree, to be evaluated in
                        the output phase.
    return      the length of the instruction (machine code bytes)
*/
{
    int len = 0;
    int state = GSTR_PASS;
    int innum = 0;

    register char *expr;

    if (!goutbuff)
    {
        goutbuff = (char *)malloc(STRALLOCSZ);
        gout_bs  = STRALLOCSZ;
    }

    goutptr = goutbuff;

    while( *str != '\0')
    {
        if(state == GSTR_PASS)
        {
            switch(*str)
            {
            case IG_START:
                state = GSTR_PROCESS;
                innum = 0;
                str++;
                break;

            case IFC_EMU8:
            case IFC_EMS7:
                len++;
                goutch(*str++);
                break;

            case IFC_EM16:
            case IFC_EMBR16:
                len += 2;
                goutch(*str++);
                break;

            default:
                goutch(*str++);
                break;
            }
        }
        else
        {
            switch(*str)
            {
            case IG_END:
                state = GSTR_PASS;
                str++;
                break;
            
            case '0':
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
                innum = (innum << 4) + (*str++) - '0';
                break;
            
            case 'a':
            case 'b':
            case 'c':
            case 'd':
            case 'e':
            case 'f':
                innum = (innum << 4) + (*str++) - 'a' + 10;
                break;
            
            case 'A':
            case 'B':
            case 'C':
            case 'D':
            case 'E':
            case 'F':
                innum = (innum << 4) + (*str++) - 'A' + 10;
                break;
            
            case IG_CPCON:
                goutxnum((unsigned int)evalr[innum].value);
                innum = 0;
                str++;
                break;

            case IG_CPEXPR:
                expr = &evalr[innum].exprstr[0];
                innum = 0;
                while(*expr != '\0')
                    goutch(*expr++);
                str++;
                break;
            
            case IG_ERROR:
                fraerror(++str);
                return 0;
            
            default:
                fraerror("invalid char in instruction generation");
                break;
            }
        }
    }

    if(goutptr > &goutbuff[2])
    {
        goutch(0);
        emit_generated_instr(goutbuff);
    }

    return len;
}

int     chtnxalph = 1, *chtcpoint = (int *)NULL, *chtnpoint = (int *)NULL;

int chtcreate(void)
/*
    description allocate and initialize a character translate
            table
    return      0 for error, subscript into chtatab to pointer
            to the allocated block
*/
{
    int *trantab, cnt;

    if(chtnxalph >= NUM_CHTA)
        return 0; /* too many */

    if( (trantab =  (int *)calloc(512, sizeof (int))) == (int *) NULL)
        return 0;

    for(cnt = 0; cnt < 512; cnt++)
        trantab[cnt] = -1;
    
    chtatab[chtnxalph] = chtnpoint = trantab;

    return chtnxalph++;
}


int chtcfind(int *chtab, char **sourcepnt, int **tabpnt, int *numret)
/*
    description find a character in a translate table
    parameters  pointer to translate table
            pointer to pointer to input string
            pointer to return value integer pointer
            pointer to numeric return
    return      status of search
*/
{
    int numval, *valaddr;
    char *sptr, cv;

    sptr = *sourcepnt;

    switch( cv = *sptr)
    {
    case '\0':
        return CF_END;

    default:
        if( chtab == (int *)NULL)
        {
            *numret = *sptr;
            *sourcepnt = ++sptr;
            return CF_NUMBER;
        }
        else
        {
            valaddr = &(chtab[cv & 0xff]);
            *sourcepnt = ++sptr;
            *tabpnt = valaddr;
            return (*valaddr == -1) ?
                CF_UNDEF : CF_CHAR;
        }
        
    case '\\':
        switch(cv =  *(++sptr) )
        {
        case '\0':
            *sourcepnt = sptr;
            return CF_INVALID;
        
        case '\'':
        case '\"':
        case '\\':
            if( chtab == (int *)NULL)
            {
                *numret = *sptr;
                *sourcepnt = ++sptr;
                return CF_NUMBER;
            }
            else
            {
                valaddr = &(chtab[(cv & 0xff) + 256]);
                *sourcepnt = ++sptr;
                *tabpnt = valaddr;
                return (*valaddr == -1) ?
                    CF_UNDEF : CF_CHAR;
            }


        default:
            if( chtab == (int *)NULL)
            {
                *sourcepnt = ++sptr;
                return CF_INVALID;
            }
            else
            {
                valaddr = &(chtab[(cv & 0xff) + 256]);
                *sourcepnt = ++sptr;
                *tabpnt = valaddr;
                return (*valaddr == -1) ?
                    CF_UNDEF : CF_CHAR;
            }

        case '0': case '1': case '2': case '3':
        case '4': case '5': case '6': case '7':
            {
                numval = cv - '0';
                cv =  *(++sptr);
                if(cv >= '0' && cv <= '7')
                {
                    numval = numval * 8 +
                        cv - '0';

                    cv = *(++sptr);
                    if(cv >= '0' && cv <= '7')
                    {
                        numval = numval * 8 +
                            cv - '0';
                        ++sptr;
                    }
                }
                *sourcepnt = sptr;
                *numret = numval & 0xff;
                return CF_NUMBER;
            }

        case 'x': case '$': case '&':
            {
                int expdig = 2, dig1 = 1;
                numval = 0;
                if (cv == '$') expdig = 4;
                if (cv == '&') expdig = 8;

                while (expdig-->0)
                {
                    switch(cv = *(++sptr))
                    {
                    case '0': case '1': case '2': case '3':
                    case '4': case '5': case '6': case '7':
                    case '8': case '9':
                        numval = numval * 16 + cv - '0';
                        break;
                    
                    case 'a': case 'b': case 'c': 
                    case 'd': case 'e': case 'f':
                        numval = numval * 16 + cv - 'a' + 10; 
                        break;
                    
                    case 'A': case 'B': case 'C':
                    case 'D': case 'E': case 'F':
                        numval = numval * 16 + cv - 'A' + 10;
                        break;
                    
                    default:
                        if (dig1)
                        {
                            *sourcepnt = sptr;
                            return CF_INVALID;
                        }
                        --sptr;
                        expdig = 0;
                        break;
                    }
                    dig1 = 0;
                }

                *sourcepnt = ++sptr;
                *numret = numval;
                return CF_NUMBER;
            }
        }
    }
    /* can't get here? */
    return 0;
}

int chtran(char **sourceptr)
{
    int numval = 0;
    int *retptr = NULL;
    char *beforeptr = *sourceptr;

    switch(chtcfind(chtcpoint, sourceptr, &retptr, &numval))
    {
    case CF_END:
    default:
        return 0;
    
    case CF_INVALID:
        fracherror("invalid character constant", beforeptr, *sourceptr);
        return 0;

    case CF_UNDEF:
        fracherror("undefined character value", beforeptr, *sourceptr);
        return 0;

    case CF_NUMBER:
        return numval;

    case CF_CHAR:
        return *retptr;
    }
}


int genstring(char *str)
/*
    description Produce 'D' records for a ascii string constant
    parameters  a character string
    return      the length of the string total (machine code bytes)
*/
{
    int rvlen = 0;

    if (!goutbuff)
    {
        goutbuff = (char *)malloc(STRALLOCSZ);
        gout_bs  = STRALLOCSZ;
    }

    goutptr = goutbuff;

    while (*str)
    {
        gout2hex(chtran(&str));
        goutch(IFC_EMU8);
        rvlen++;
    }

    if(goutptr > &goutbuff[2])
    {
        goutch(0);
        emit_generated_instr(goutbuff);
    }

    return rvlen;
}
    
static char *pepolptr;
static int pepolcnt;
static int etop;
static int etopseg;
#define STACKALLOWANCE (8) /* number of level used outside polish expr */

static inline void polout(char ch)
/*
    description output a character to a evar[?].exprstr array
    globals     parser expression to polish pointer pepolptr
*/
{
    if(pepolcnt > 1)
    {
        *pepolptr++ = ch;
        pepolcnt --;
    }
    else
    {
        *pepolptr = '\0';
        fraerror("overflow in polish expression conversion");
    }
}


void pevalexpr(int sub, int exn)
/*
    description evaluate and save the results of an expression tree
    parameters  the subscript to the evalr element to place the results
                the subscript of the root node of a parser expression tree
    globals     the evaluation results array
                the expression stack
                the expression tree node array
    return      in evalr[sub].seg == SSG_UNDEF if the polish expression
                conversion overflowed, or any undefined symbols were
                referenced.
*/
{
    etop = 0;
    etopseg = SSG_UNUSED;
    estkm1p = &estk[0];

    pepolptr = &evalr[sub].exprstr[0];
    pepolcnt = PPEXPRLEN;

    if(pepolcon(exn))
    {
        evalr[sub].seg = etopseg;
        evalr[sub].value = etop;
        polout('\0');
    }
    else
    {
        evalr[sub].exprstr[0] = '\0';
        evalr[sub].seg = SSG_UNDEF;
    }
}

void polnumout(unsigned int inv)
/*
    description output a long constant to a polish expression
*/
{
    if( inv > 15)
        polnumout(inv >> 4);
    polout(hexch((int) inv ));
}

int pepolcon(int esub)
/*
    description convert an expression tree to polish notation
            and do a preliminary evaluation of the numeric value
            of the expression
    parameters  the subscript of an expression node
    globals     the expression stack
            the polish expression string in an evalr element
    return      False if the expression stack overflowed

            The expression stack top contains the
            value and segment for the result of the expression
            which are propgated along as numeric operators are
            evaluated.  Undefined references result in an
            undefined result.
*/
{
    switch(enode[esub].evs)
    {
    case  PCCASE_UN:
        {
            if( ! pepolcon(enode[esub].left))
                return FALSE;

            polout(enode[esub].op);

            switch(enode[esub].op)
            {
#include "fraeuni.h"
            }
        }
        break;

    case  PCCASE_BIN:
        {
            if( ! pepolcon(enode[esub].left))
                return FALSE;

            polout(IFC_LOAD);

            if(estkm1p >= &estk[PESTKDEPTH-1-STACKALLOWANCE])
            {
                fraerror("expression stack overflow");
                return FALSE;
            }

            (++estkm1p)->v = etop;
            estkm1p->s = etopseg;
            etopseg = SSG_UNUSED;   
            etop = 0;

            if( ! pepolcon(enode[esub].right))
                return FALSE;

            polout(enode[esub].op);

            if(estkm1p->s != SSG_ABS)
                etopseg = estkm1p->s;

            switch(enode[esub].op)
            {
#define FRAERR fraerror
#include "fraebin.h"
            }
        }
        break;

    case  PCCASE_DEF:
        if(enode[esub].sym->seg > 0)
        {
            polnumout(1L);
            etop = 1;
            etopseg = SSG_ABS;
        }
        else
        {
            polnumout(0L);
            etop = 0;
            etopseg = SSG_ABS;
        }
        break;

    case  PCCASE_SYMB:
        etop = (enode[esub].sym)->value;
        etopseg = (enode[esub].sym)->seg;
        if(etopseg == SSG_EQU ||
           etopseg == SSG_SET ) 
        {
            etopseg = SSG_ABS;
            polnumout((unsigned int)(enode[esub].sym)->value);
        }
        else
        {
            polnumout((unsigned int)(enode[esub].sym)->symnum);
            polout(IFC_SYMB);
        }
        break;
            
    case  PCCASE_PROGC:
        polout(IFC_PROGCTR);
        etop = locctr >> 1;
        etopseg = SSG_ABS;
        break;
            
    case  PCCASE_CONS:
        polnumout((unsigned int)enode[esub].val);
        etop = enode[esub].val;
        etopseg = SSG_ABS;
        break;

    }
    return TRUE;
}