double evaluate(char *expr)
{
int i = 0;
char ch;
memset(&buf[0], 0, MAXLEN);
pos = 0;
while((ch = *expr++) != '\0') {
if(!isspace(ch)) {
buf[i++] = ch;
}
}
return addexpr();
}
double atom()
{
double res = NAN;
if(isdigit(top())) {
res = literal();
} else if(top() == '(') {
next();
res = addexpr();
next();
} else if(top() == '-') {
next();
res = -atom();
}
return res;
}
void dereference(void) /* assume address has already been pushed */
{
while(tokeq(".") || tokeq("[") || tokeq("^"))
{
if(tokeq("."))
{
scan();
g_pop_bx();
g_add_bx(member());
g_push_bx();
}
else if(tokeq("["))
{
scan();
addexpr();
if(tokeq("]"))
{
scan();
g_pop_ax();
g_pop_bx();
g_add_bx_ax();
g_push_bx();
} else
{
error("Missing ]");
}
}
else if(tokeq("^"))
{
scan();
g_pop_bx();
g_mov_ax_BX();
g_push_ax();
}
}
}
void compexpr(int findvar)
{
char x, y;
if (findvar)
{
if(tokeq("*"))
{
scan();
shouldsym = name(1);
} else
{
shouldsym = name(0);
}
g_pop_bx();
g_push_BX();
} else
{
addexpr();
}
while(tokeq("=") || tokeq("<>") || tokeq(">") ||
tokeq(">=") || tokeq("<") || tokeq("<="))
{
x = token[0]; y = token[1];
scan();
addexpr();
if(x == '=')
{
g_pop_ax();
g_pop_dx();
g_sub_ax_dx();
g_jz(+3);
g_xor_ax_ax();
g_dec_ax();
g_label(); g_inc_ax();
g_push_ax();
}
if(x == '<' && y == '>')
{
g_pop_ax();
g_pop_dx();
g_xor_cx_cx();
g_sub_ax_dx();
g_jz(+1);
g_inc_cx();
g_label(); g_push_cx();
}
if(x == '<' && y == 0)
{
g_pop_dx();
g_pop_ax();
g_xor_cx_cx();
g_cmp_ax_dx();
g_jge(+1);
g_inc_cx();
g_label(); g_push_cx();
}
if(x == '>' && y == 0)
{
g_pop_dx();
g_pop_ax();
g_xor_cx_cx();
g_cmp_ax_dx();
g_jle(+1);
g_inc_cx();
g_label(); g_push_cx();
}
if(x == '<' && y == '=')
{
g_pop_dx();
g_pop_ax();
g_xor_cx_cx();
g_cmp_ax_dx();
g_jg(+1);
g_inc_cx();
g_label(); g_push_cx();
}
if(x == '>' && y == '=')
{
g_pop_dx();
g_pop_ax();
g_xor_cx_cx();
g_cmp_ax_dx();
g_jl(+1);
g_inc_cx();
g_label(); g_push_cx();
}
}
}
