]> Shamusworld >> Repos - rmac/blobdiff - expr.c
(c) message in header files and doc mini adjustments.
[rmac] / expr.c
diff --git a/expr.c b/expr.c
index 23f6a14afcbb0c46561c101b6d0e43e382acbb56..44fd892bab2d0594170dd834741b411dc9498284 100644 (file)
--- a/expr.c
+++ b/expr.c
@@ -1,9 +1,9 @@
 //
-// RMAC - Reboot's Macro Assembler for the Atari Jaguar Console System
+// RMAC - Reboot's Macro Assembler for all Atari computers
 // EXPR.C - Expression Analyzer
-// Copyright (C) 199x Landon Dyer, 2011 Reboot and Friends
+// Copyright (C) 199x Landon Dyer, 2011-2017 Reboot and Friends
 // RMAC derived from MADMAC v1.07 Written by Landon Dyer, 1986
-// Source Utilised with the Kind Permission of Landon Dyer
+// Source utilised with the kind permission of Landon Dyer
 //
 
 #include "expr.h"
 #include "listing.h"
 #include "mach.h"
 #include "procln.h"
-#include "risca.h"
+#include "riscasm.h"
 #include "sect.h"
 #include "symbol.h"
 #include "token.h"
 
-#define DEF_KW                                                 // Declare keyword values 
-#include "kwtab.h"                                             // Incl generated keyword tables & defs
+#define DEF_KW                                         // Declare keyword values
+#include "kwtab.h"                                     // Incl generated keyword tables & defs
 
-static char tokcl[128];                                        // Generated table of token classes
-static VALUE evstk[EVSTACKSIZE];               // Evaluator value stack
-static WORD evattr[EVSTACKSIZE];               // Evaluator attribute stack
+// N.B.: The size of tokenClass should be identical to the largest value of
+//       a token; we're assuming 256 but not 100% sure!
+static char tokenClass[256];           // Generated table of token classes
+static VALUE evstk[EVSTACKSIZE];       // Evaluator value stack
+static WORD evattr[EVSTACKSIZE];       // Evaluator attribute stack
 
 // Token-class initialization list
 char itokcl[] = {
-       0,                                                                      // END
-       CONST, SYMBOL, 0,                                       // ID 
-       '(', '[', '{', 0,                                       // OPAR
-       ')', ']', '}', 0,                                       // CPAR 
-       CR_DEFINED, CR_REFERENCED,                      // SUNARY (special unary)
+       0,                                                              // END
+       CONST, SYMBOL, 0,                               // ID
+       '(', '[', '{', 0,                               // OPAR
+       ')', ']', '}', 0,                               // CPAR
+       CR_DEFINED, CR_REFERENCED,              // SUNARY (special unary)
        CR_STREQ, CR_MACDEF,
-       CR_DATE, CR_TIME, 0,
-       '!', '~', UNMINUS, 0,                           // UNARY
-       '*', '/', '%', 0,                                       // MULT 
-       '+', '-', 0,                                            // ADD 
-       SHL, SHR, 0,                                            // SHIFT 
-       LE, GE, '<', '>', NE, '=', 0,           // REL 
-       '&', 0,                                                         // AND 
-       '^', 0,                                                         // XOR 
-       '|', 0,                                                         // OR 
-       1                                                                       // (the end) 
+       CR_DATE, CR_TIME,
+       CR_ABSCOUNT, 0,
+       '!', '~', UNMINUS, 0,                   // UNARY
+       '*', '/', '%', 0,                               // MULT
+       '+', '-', 0,                                    // ADD
+       SHL, SHR, 0,                                    // SHIFT
+       LE, GE, '<', '>', NE, '=', 0,   // REL
+       '&', 0,                                                 // AND
+       '^', 0,                                                 // XOR
+       '|', 0,                                                 // OR
+       1                                                               // (the end)
 };
 
 const char missym_error[] = "missing symbol";
 const char str_error[] = "missing symbol or string";
 
 // Convert expression to postfix
-static TOKEN * tk;                                             // Deposit tokens here (this is really a
-                                                                               // pointer to exprbuf from direct.c)
-static symbolNum;                                              // Pointer to the entry in symbolPtr[]
+static TOKEN * evalTokenBuffer;                // Deposit tokens here (this is really a
+                                                                       // pointer to exprbuf from direct.c)
+                                                                       // (Can also be from others, like
+                                                                       // riscasm.c)
+static int symbolNum;                          // Pointer to the entry in symbolPtr[]
 
 
 //
-// Obtain a String Value
+// Obtain a string value
 //
 static VALUE str_value(char * p)
 {
@@ -68,23 +73,22 @@ static VALUE str_value(char * p)
 
 
 //
-// Initialize Expression Analyzer
+// Initialize expression analyzer
 //
-void init_expr(void)
+void InitExpression(void)
 {
-       int i;                                                                  // Iterator
-       char * p;                                                               // Token pointer
+       // Initialize token-class table (all set to END)
+       for(int i=0; i<256; i++)
+               tokenClass[i] = END;
 
-       // Initialize token-class table
-       for(i=0; i<128; i++)                                    // Mark all entries END
-               tokcl[i] = END;
+       int i = 0;
 
-       for(i=0, p=itokcl; *p!=1; p++)
+       for(char * p=itokcl; *p!=1; p++)
        {
                if (*p == 0)
                        i++;
-               else 
-                       tokcl[(int)(*p)] = (char)i;
+               else
+                       tokenClass[(int)(*p)] = (char)i;
        }
 
        symbolNum = 0;
@@ -100,15 +104,15 @@ int expr0(void)
 
        if (expr1() != OK)
                return ERROR;
-       
-       while (tokcl[*tok] >= MULT)
+
+       while (tokenClass[*tok] >= MULT)
        {
                t = *tok++;
 
                if (expr1() != OK)
                        return ERROR;
 
-               *tk++ = t;
+               *evalTokenBuffer++ = t;
        }
 
        return OK;
@@ -117,6 +121,9 @@ int expr0(void)
 
 //
 // Unary operators (detect unary '-')
+// ggn: If expression starts with a plus then also eat it up.
+//      For some reason the parser gets confused when this happens and
+//      emits a "bad expression".
 //
 int expr1(void)
 {
@@ -127,9 +134,9 @@ int expr1(void)
        WORD w;
        int j;
 
-       class = tokcl[*tok];
+       class = tokenClass[*tok];
 
-       if (*tok == '-' || class == UNARY)
+       if (*tok == '-' || *tok == '+' || class == UNARY)
        {
                t = *tok++;
 
@@ -139,32 +146,32 @@ int expr1(void)
                if (t == '-')
                        t = UNMINUS;
 
-               *tk++ = t;
+               *evalTokenBuffer++ = t;
        }
        else if (class == SUNARY)
        {
                switch ((int)*tok++)
                {
+               case CR_ABSCOUNT:
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = (LONG)sect[ABS].sloc;
+                       break;
                case CR_TIME:
-                       *tk++ = CONST;
-                       *tk++ = dos_time();
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = dos_time();
                        break;
                case CR_DATE:
-                       *tk++ = CONST;
-                       *tk++ = dos_date();
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = dos_date();
                        break;
                case CR_MACDEF:                                    // ^^macdef <macro-name>
                        if (*tok++ != SYMBOL)
                                return error(missym_error);
 
-#if 0
-                       p = (char *)*tok++;
-#else
                        p = string[*tok++];
-#endif
                        w = (lookup(p, MACRO, 0) == NULL ? 0 : 1);
-                       *tk++ = CONST;
-                       *tk++ = (TOKEN)w;
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = (TOKEN)w;
                        break;
                case CR_DEFINED:
                        w = DEFINED;
@@ -175,29 +182,17 @@ getsym:
                        if (*tok++ != SYMBOL)
                                return error(missym_error);
 
-#if 0
-                       p = (char *)*tok++;
-#else
                        p = string[*tok++];
-#endif
-                       j = 0;
-
-                       if (*p == '.')
-                               j = curenv;
-
+                       j = (*p == '.' ? curenv : 0);
                        w = ((sy = lookup(p, LABEL, j)) != NULL && (sy->sattr & w) ? 1 : 0);
-                       *tk++ = CONST;
-                       *tk++ = (TOKEN)w;
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = (TOKEN)w;
                        break;
                case CR_STREQ:
                        if (*tok != SYMBOL && *tok != STRING)
                                return error(str_error);
 
-#if 0
-                       p = (char *)tok[1];
-#else
                        p = string[tok[1]];
-#endif
                        tok +=2;
 
                        if (*tok++ != ',')
@@ -206,20 +201,16 @@ getsym:
                        if (*tok != SYMBOL && *tok != STRING)
                                return error(str_error);
 
-#if 0
-                       p2 = (char *)tok[1];
-#else
-                       p = string[tok[1]];
-#endif
+                       p2 = string[tok[1]];
                        tok += 2;
 
                        w = (WORD)(!strcmp(p, p2));
-                       *tk++ = CONST;
-                       *tk++ = (TOKEN)w;
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = (TOKEN)w;
                        break;
                }
        }
-       else 
+       else
                return expr2();
 
        return OK;
@@ -238,20 +229,12 @@ int expr2(void)
        switch ((int)*tok++)
        {
        case CONST:
-               *tk++ = CONST;
-               *tk++ = *tok++;
+               *evalTokenBuffer++ = CONST;
+               *evalTokenBuffer++ = *tok++;
                break;
        case SYMBOL:
-#if 0
-               p = (char *)*tok++;
-#else
                p = string[*tok++];
-#endif
-               j = 0;
-
-               if (*p == '.')
-                       j = curenv;
-
+               j = (*p == '.' ? curenv : 0);
                sy = lookup(p, LABEL, j);
 
                if (sy == NULL)
@@ -260,29 +243,21 @@ int expr2(void)
                // Check register bank usage
                if (sy->sattre & EQUATEDREG)
                {
-                       if ((regbank == BANK_0) && (sy->sattre & BANK_1) && !altbankok)   
+                       if ((regbank == BANK_0) && (sy->sattre & BANK_1) && !altbankok)
                                warns("equated symbol \'%s\' cannot be used in register bank 0", sy->sname);
 
                        if ((regbank == BANK_1) && (sy->sattre & BANK_0) && !altbankok)
                                warns("equated symbol \'%s\' cannot be used in register bank 1", sy->sname);
                }
 
-               *tk++ = SYMBOL;
-#if 0
-               *tk++ = (TOKEN)sy;
-#else
-               *tk++ = symbolNum;
+               *evalTokenBuffer++ = SYMBOL;
+               *evalTokenBuffer++ = symbolNum;
                symbolPtr[symbolNum] = sy;
                symbolNum++;
-#endif
                break;
        case STRING:
-               *tk++ = CONST;
-#if 0
-               *tk++ = str_value((char *)*tok++);
-#else
-               *tk++ = str_value(string[*tok++]);
-#endif
+               *evalTokenBuffer++ = CONST;
+               *evalTokenBuffer++ = str_value(string[*tok++]);
                break;
        case '(':
                if (expr0() != OK)
@@ -301,19 +276,31 @@ int expr2(void)
 
                break;
        case '$':
-               *tk++ = ACONST;                                    // Attributed const
-               *tk++ = sloc;                                      // Current location
-               *tk++ = cursect | DEFINED;                         // Store attribs
+               *evalTokenBuffer++ = ACONST;                            // Attributed const
+               *evalTokenBuffer++ = sloc;                                      // Current location
+               *evalTokenBuffer++ = cursect | DEFINED;         // Store attribs
                break;
        case '*':
-               *tk++ = ACONST;                                    // Attributed const
+               *evalTokenBuffer++ = ACONST;                            // Attributed const
 
-               if (orgactive)
-                       *tk++ = orgaddr;
-               else
-                       *tk++ = pcloc;                                  // Location at start of line
+               // pcloc == location at start of line
+               *evalTokenBuffer++ = (orgactive ? orgaddr : pcloc);
+               // '*' takes attributes of current section, not ABS!
+               *evalTokenBuffer++ = cursect | DEFINED;
+               break;
+       case '{':
+               if (expr0() != OK)                                                      // Eat up first parameter (register or immediate)
+                       return ERROR;
+
+               if (*tok++ != ':')                                                      // Demand a ':' there
+                       return error("missing colon ':'");
+
+               if (expr0() != OK)                                                      // Eat up second parameter (register or immediate)
+                       return ERROR;
+
+               if (*tok++ != '}')
+                       return error("missing close bracket '}'");
 
-               *tk++ = ABS | DEFINED;                             // Store attribs
                break;
        default:
                return error("bad expression");
@@ -330,121 +317,155 @@ int expr(TOKEN * otk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
 {
        // Passed in values (once derefenced, that is) can all be zero. They are
        // there so that the expression analyzer can fill them in as needed. The
-       // expression analyzer gets its input from "tok", and not from anything
-       // passed in by the user.
-       SYM * sy;
+       // expression analyzer gets its input from the global token pointer "tok",
+       // and not from anything passed in by the user.
+       SYM * symbol;
        char * p;
        int j;
 
-       tk = otk;                       // Set token pointer to 'exprbuf' (direct.c)
-                                               // Also set in various other places too (risca.c, e.g.)
-//     symbolNum = 0;          // Set symbol number in symbolPtr[] to 0
+       evalTokenBuffer = otk;  // Set token pointer to 'exprbuf' (direct.c)
+                                                       // Also set in various other places too (riscasm.c, e.g.)
 
+//printf("expr(): tokens 0-2: %i %i %i (%c %c %c); tc[2] = %i\n", tok[0], tok[1], tok[2], tok[0], tok[1], tok[2], tokenClass[tok[2]]);
        // Optimize for single constant or single symbol.
-       if ((tok[1] == EOL)
+       // Shamus: Subtle bug here. EOL token is 101; if you have a constant token
+       //         followed by the value 101, it will trigger a bad evaluation here.
+       //         This is probably a really bad assumption to be making here...!
+       //         (assuming tok[1] == EOL is a single token that is)
+       //         Seems that even other tokens (SUNARY type) can fuck this up too.
+//     if ((tok[1] == EOL)
+       if ((tok[1] == EOL && (tok[0] != CONST && tokenClass[tok[0]] != SUNARY))
                || (((*tok == CONST || *tok == SYMBOL) || (*tok >= KW_R0 && *tok <= KW_R31))
-               && (tokcl[tok[2]] < UNARY)))
+               && (tokenClass[tok[2]] < UNARY)))
        {
                if (*tok >= KW_R0 && *tok <= KW_R31)
                {
-                       *tk++ = CONST;
-                       *tk++ = *a_value = (*tok - KW_R0);
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = *a_value = (*tok - KW_R0);
                        *a_attr = ABS | DEFINED;
 
                        if (a_esym != NULL)
                                *a_esym = NULL;
 
                        tok++;
-                       *tk++ = ENDEXPR;
-                       return OK;
                }
                else if (*tok == CONST)
                {
-                       *tk++ = CONST;
-                       *tk++ = *a_value = tok[1];
+                       *evalTokenBuffer++ = CONST;
+                       *evalTokenBuffer++ = *a_value = tok[1];
                        *a_attr = ABS | DEFINED;
 
                        if (a_esym != NULL)
                                *a_esym = NULL;
+
+                       tok += 2;
+//printf("Quick eval in expr(): CONST = %i, tokenClass[tok[2]] = %i\n", *a_value, tokenClass[*tok]);
                }
                else if (*tok == '*')
                {
-                       *tk++ = CONST;
+                       *evalTokenBuffer++ = CONST;
 
                        if (orgactive)
-                               *tk++ = *a_value = orgaddr;
+                               *evalTokenBuffer++ = *a_value = orgaddr;
                        else
-                               *tk++ = *a_value = pcloc;
+                               *evalTokenBuffer++ = *a_value = pcloc;
 
-                       *a_attr = ABS | DEFINED;
-                       //*tk++ = 
+                       // '*' takes attributes of current section, not ABS!
+                       *a_attr = cursect | DEFINED;
 
                        if (a_esym != NULL)
                                *a_esym = NULL;
 
-                       tok--;
+                       tok++;
                }
-               else
+               else if (*tok == STRING || *tok == SYMBOL)
                {
-#if 0
-                       p = (char *)tok[1];
-#else
                        p = string[tok[1]];
+                       j = (*p == '.' ? curenv : 0);
+                       symbol = lookup(p, LABEL, j);
+#if 0
+printf("eval: Looking up symbol (%s) [=%08X]\n", p, symbol);
+if (symbol)
+       printf("      attr=%04X, attre=%08X, val=%i, name=%s\n", symbol->sattr, symbol->sattre, symbol->svalue, symbol->sname);
 #endif
-                       j = 0;
-
-                       if (*p == '.')
-                               j = curenv;
 
-                       sy = lookup(p, LABEL, j);
+                       if (symbol == NULL)
+                               symbol = NewSymbol(p, LABEL, j);
 
-                       if (sy == NULL)
-                               sy = NewSymbol(p, LABEL, j);
+                       symbol->sattr |= REFERENCED;
 
-                       sy->sattr |= REFERENCED;
+                       // Check for undefined register equates, but only if it's not part
+                       // of a #<SYMBOL> construct, as it could be that the label that's
+                       // been undefined may later be used as an address label--which
+                       // means it will be fixed up later, and thus, not an error.
+                       if ((symbol->sattre & UNDEF_EQUR) && !riscImmTokenSeen)
+                       {
+                               errors("undefined register equate '%s'", symbol->sname);
+//if we return right away, it returns some spurious errors...
+//                             return ERROR;
+                       }
 
                        // Check register bank usage
-                       if (sy->sattre & EQUATEDREG)
+                       if (symbol->sattre & EQUATEDREG)
                        {
-                               if ((regbank == BANK_0) && (sy->sattre & BANK_1) && !altbankok)   
-                                       warns("equated symbol \'%s\' cannot be used in register bank 0", sy->sname);
+                               if ((regbank == BANK_0) && (symbol->sattre & BANK_1) && !altbankok)
+                                       warns("equated symbol '%s' cannot be used in register bank 0", symbol->sname);
 
-                               if ((regbank == BANK_1) && (sy->sattre & BANK_0) && !altbankok)
-                                       warns("equated symbol \'%s\' cannot be used in register bank 1", sy->sname);
+                               if ((regbank == BANK_1) && (symbol->sattre & BANK_0) && !altbankok)
+                                       warns("equated symbol '%s' cannot be used in register bank 1", symbol->sname);
                        }
 
-                       *tk++ = SYMBOL;
+                       *evalTokenBuffer++ = SYMBOL;
 #if 0
-                       *tk++ = (TOKEN)sy;
+                       *evalTokenBuffer++ = (TOKEN)symbol;
 #else
-                       *tk++ = symbolNum;
-                       symbolPtr[symbolNum] = sy;
+/*
+While this approach works, it's wasteful. It would be better to use something
+that's already available, like the symbol "order defined" table (which needs to
+be converted from a linked list into an array).
+*/
+                       *evalTokenBuffer++ = symbolNum;
+                       symbolPtr[symbolNum] = symbol;
                        symbolNum++;
 #endif
 
-                       if (sy->sattr & DEFINED)
-                               *a_value = sy->svalue;
+                       if (symbol->sattr & DEFINED)
+                               *a_value = symbol->svalue;
                        else
                                *a_value = 0;
 
-                       if (sy->sattre & EQUATEDREG) 
+/*
+All that extra crap that was put into the svalue when doing the equr stuff is
+thrown away right here. What the hell is it for?
+*/
+                       if (symbol->sattre & EQUATEDREG)
                                *a_value &= 0x1F;
 
-                       *a_attr = (WORD)(sy->sattr & ~GLOBAL);
+                       *a_attr = (WORD)(symbol->sattr & ~GLOBAL);
+
+                       if ((symbol->sattr & (GLOBAL | DEFINED)) == GLOBAL
+                               && a_esym != NULL)
+                               *a_esym = symbol;
 
-                       if ((sy->sattr & (GLOBAL | DEFINED)) == GLOBAL && a_esym != NULL)
-                               *a_esym = sy;
+                       tok += 2;
+               }
+               else
+               {
+                       // Unknown type here... Alert the user!,
+                       error("undefined RISC register in expression");
+                       // Prevent spurious error reporting...
+                       tok++;
+                       return ERROR;
                }
 
-               tok += 2;
-               *tk++ = ENDEXPR;
+               *evalTokenBuffer++ = ENDEXPR;
                return OK;
        }
 
        if (expr0() != OK)
                return ERROR;
 
-       *tk++ = ENDEXPR;
+       *evalTokenBuffer++ = ENDEXPR;
        return evexpr(otk, a_value, a_attr, a_esym);
 }
 
@@ -457,26 +478,21 @@ int expr(TOKEN * otk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
 //
 int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
 {
-       WORD * sattr;
-       VALUE * sval;
        WORD attr;
        SYM * sy;
-       SYM * esym;
-       WORD sym_seg;
-
-       sval = evstk;                                                   // (Empty) initial stack
-       sattr = evattr;
-       esym = NULL;                                                    // No external symbol involved
-       sym_seg = 0;
+       VALUE * sval = evstk;                                   // (Empty) initial stack
+       WORD * sattr = evattr;
+       SYM * esym = NULL;                                              // No external symbol involved
+       WORD sym_seg = 0;
 
        while (*tk != ENDEXPR)
        {
                switch ((int)*tk++)
                {
                case SYMBOL:
-//                     sy = (SYM *)*tk++;
+//printf("evexpr(): SYMBOL\n");
                        sy = symbolPtr[*tk++];
-                       sy->sattr |= REFERENCED;                // Set "referenced" bit 
+                       sy->sattr |= REFERENCED;                // Set "referenced" bit
 
                        if (!(sy->sattr & DEFINED))
                        {
@@ -500,78 +516,88 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        }
                        else
                        {
-                               *++sval = 0;                            // 0 for undefined symbols 
+                               *++sval = 0;                            // 0 for undefined symbols
                        }
 
                        *++sattr = (WORD)(sy->sattr & ~GLOBAL); // Push attribs
-                       sym_seg = (WORD)(sy->sattr & (TEXT | DATA | BSS));
+                       sym_seg = (WORD)(sy->sattr & TDB);
                        break;
                case CONST:
+//printf("evexpr(): CONST = %i\n", *tk);
                        *++sval = *tk++;                                // Push value
                        *++sattr = ABS | DEFINED;               // Push simple attribs
                        break;
                case ACONST:
+//printf("evexpr(): ACONST = %i\n", *tk);
                        *++sval = *tk++;                                // Push value
                        *++sattr = (WORD)*tk++;                 // Push attribs
                        break;
 
                        // Binary "+" and "-" matrix:
-                       // 
+                       //
                        //                ABS    Sect     Other
                        //     ----------------------------
                        //   ABS     |  ABS   |  Sect  |  Other |
                        //   Sect    |  Sect  |  [1]   |  Error |
                        //   Other   |  Other |  Error |  [1]   |
                        //      ----------------------------
-                       // 
+                       //
                        //   [1] + : Error
                        //       - : ABS
                case '+':
+//printf("evexpr(): +\n");
                        --sval;                                                 // Pop value
-                       --sattr;                                                // Pop attrib 
+                       --sattr;                                                // Pop attrib
+//printf("--> N+N: %i + %i = ", *sval, sval[1]);
                        *sval += sval[1];                               // Compute value
+//printf("%i\n", *sval);
 
-                       if (!(*sattr & (TEXT | DATA | BSS)))
+                       if (!(*sattr & TDB))
                                *sattr = sattr[1];
-                       else if (sattr[1] & (TEXT | DATA | BSS))
+                       else if (sattr[1] & TDB)
                                return error(seg_error);
 
                        break;
                case '-':
+//printf("evexpr(): -\n");
                        --sval;                                                 // Pop value
-                       --sattr;                                                // Pop attrib 
+                       --sattr;                                                // Pop attrib
+//printf("--> N-N: %i - %i = ", *sval, sval[1]);
                        *sval -= sval[1];                               // Compute value
+//printf("%i\n", *sval);
 
-                       attr = (WORD)(*sattr & (TEXT | DATA | BSS));
-
+                       attr = (WORD)(*sattr & TDB);
+#if 0
+printf("EVEXPR (-): sym1 = %X, sym2 = %X\n", attr, sattr[1]);
+#endif
+                       // If symbol1 is ABS, take attributes from symbol2
                        if (!attr)
                                *sattr = sattr[1];
-                       else if (sattr[1] & (TEXT | DATA | BSS))
-                       {
-                               if (!(attr & sattr[1]))
-                                       return error(seg_error);
-                               else
-                                       *sattr &= ~(TEXT | DATA | BSS);
-                       }
+                       // Otherwise, they're both TDB and so attributes cancel out
+                       else if (sattr[1] & TDB)
+                               *sattr &= ~TDB;
 
                        break;
                // Unary operators only work on ABS items
                case UNMINUS:
-                       if (*sattr & (TEXT | DATA | BSS))
+//printf("evexpr(): UNMINUS\n");
+                       if (*sattr & TDB)
                                error(seg_error);
 
                        *sval = -(int)*sval;
                        *sattr = ABS | DEFINED;                 // Expr becomes absolute
                        break;
                case '!':
-                       if (*sattr & (TEXT | DATA | BSS))
+//printf("evexpr(): !\n");
+                       if (*sattr & TDB)
                                error(seg_error);
 
                        *sval = !*sval;
                        *sattr = ABS | DEFINED;                 // Expr becomes absolute
                        break;
                case '~':
-                       if (*sattr & (TEXT | DATA | BSS))
+//printf("evexpr(): ~\n");
+                       if (*sattr & TDB)
                                error(seg_error);
 
                        *sval = ~*sval;
@@ -580,8 +606,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                // Comparison operators must have two values that
                // are in the same segment, but that's the only requirement.
                case LE:
-                       --sattr;
-                       --sval;
+//printf("evexpr(): LE\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -590,8 +617,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        *sval = *sval <= sval[1];
                        break;
                case GE:
-                       --sattr;
-                       --sval;
+//printf("evexpr(): GE\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -600,8 +628,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        *sval = *sval >= sval[1];
                        break;
                case '>':
-                       --sattr;
-                       --sval;
+//printf("evexpr(): >\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -610,8 +639,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        *sval = *sval > sval[1];
                        break;
                case '<':
-                       --sattr;
-                       --sval;
+//printf("evexpr(): <\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -620,8 +650,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        *sval = *sval < sval[1];
                        break;
                case NE:
-                       --sattr;
-                       --sval;
+//printf("evexpr(): NE\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -630,8 +661,9 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        *sval = *sval != sval[1];
                        break;
                case '=':
-                       --sattr;
-                       --sval;
+//printf("evexpr(): =\n");
+                       sattr--;
+                       sval--;
 
                        if ((*sattr & TDB) != (sattr[1] & TDB))
                                error(seg_error);
@@ -642,6 +674,7 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                // All other binary operators must have two ABS items
                // to work with.  They all produce an ABS value.
                default:
+//printf("evexpr(): default\n");
                        // GH - Removed for v1.0.15 as part of the fix for indexed loads.
                        //if ((*sattr & (TEXT|DATA|BSS)) || (*--sattr & (TEXT|DATA|BSS)))
                        //error(seg_error);
@@ -650,22 +683,30 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                        switch ((int)tk[-1])
                        {
                        case '*':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
+//printf("--> NxN: %i x %i = ", *sval, sval[1]);
                                *sval *= sval[1];
+//printf("%i\n", *sval);
                                break;
                        case '/':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
 
                                if (sval[1] == 0)
                                        return error("divide by zero");
 
-                               *sval /= sval[1];
+//printf("--> N/N: %i / %i = ", sval[0], sval[1]);
+                               // Compiler is picky here: Without casting these, it discards
+                               // the sign if dividing a negative # by a positive one,
+                               // creating a bad result. :-/
+                               // Probably a side effect of using VALUE intead of ints.
+                               *sval = (int)sval[0] / (int)sval[1];
+//printf("%i\n", *sval);
                                break;
                        case '%':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
 
                                if (sval[1] == 0)
                                        return error("mod (%) by zero");
@@ -673,28 +714,28 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
                                *sval %= sval[1];
                                break;
                        case SHL:
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
                                *sval <<= sval[1];
                                break;
                        case SHR:
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
                                *sval >>= sval[1];
                                break;
                        case '&':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
                                *sval &= sval[1];
                                break;
                        case '^':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
                                *sval ^= sval[1];
                                break;
                        case '|':
-                               --sval;
-                               --sattr;                                        // Pop attrib 
+                               sval--;
+                               sattr--;                                        // Pop attrib
                                *sval |= sval[1];
                                break;
                        default:
@@ -712,10 +753,11 @@ int evexpr(TOKEN * tk, VALUE * a_value, WORD * a_attr, SYM ** a_esym)
        // sym_seg added in 1.0.16 to solve a problem with forward symbols in
        // expressions where absolute values also existed. The absolutes were
        // overiding the symbol segments and not being included :(
-       //*a_attr = *sattr | sym_seg;                                        // Copy value + attrib
+       //*a_attr = *sattr | sym_seg;           // Copy value + attrib
 
        *a_attr = *sattr;                                               // Copy value + attrib
        *a_value = *sval;
 
        return OK;
 }
+