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#include "spasm.h"
/**
* Expressions in SPASM are implemented in a totally broken manner.
*
* The result of an expression is the value of its initial argument
* after executing the operation of the last operand with the last argument.
*
* For example dw $cafeba00+2+4 is not equal to dw $cafeba06
* but to dw $cafeba04.
* Likewise, dw $2+$cafeba00+4 is not equal to dw $cafeba06
* but to dw $6 !
*/
unsigned int spasm_eval(char *expr)
{
char *cset = "+-><&|*!";
char *csetp;
char *cp;
int ok;
int t = T_INTEGER;
char sbuf[128];
if(strcmp(expr, "*") == 0) // Return current return address
return curPc;
if(strcasecmp(curIns, "incbin") == 0)
return 0; // If current instruction is incbin, do not evaluate.
if(*expr == '"' || *expr == '\'')
return 0; // I won't even try to evaluate strings!
int ispan = strcspn(expr, cset);
csetp = cset;
ok = 0; // ok will be 0 if we found no operator, 1 if we found it
char op = '?';
cp = NULL;
while(*csetp)
{
char *tcp = strrchr(expr, *csetp);
if(tcp) // Found operator
{
if(tcp > cp)
cp = tcp;
if(*cp == '>')
{
if(*(cp-1) != '>')
instruction_error("Bad operator");
}
if(*cp == '<')
{
if(*(cp-1) != '<')
instruction_error("Bad operator");
}
cp++;
ok = 1;
op = *csetp;
break;
}
csetp++;
}
unsigned int one = 0;
unsigned int two = 0;
memcpy(sbuf, expr, ispan);
sbuf[ispan] = '\0';
if(strlen(sbuf) == 0)
strcpy(sbuf, "0");
//instruction_error("Bad expression");
//printf("sbuf = %s\n", sbuf);
one = asm_atoi(sbuf);
t = atoiT[insArgc];
if(ok)
{
strcpy(sbuf, cp);
if(strlen(sbuf) == 0)
instruction_error("Bad expression");
two = asm_atoi(sbuf);
if(t == T_INTEGER)
t = atoiT[insArgc];
}
atoiT[insArgc] = t;
switch(op)
{
case '+':
return one + two;
break;
case '-':
return one - two;
break;
case '<':
return one << two;
break;
case '>':
return one >> two;
break;
case '&':
return one & two;
break;
case '|':
case '!':
return one | two;
break;
case '*':
return one * two;
break;
}
return one;
}
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