// Parse a character constant of the form 'c'
void chrconst(void) {
fetchc();
symval = inchar;
sym = s_nval;
fetchc();
if (inchar != '\'') expectedchar('\'');
fetchc(); // consume "
}
// The switch statement: execute one of N statements based on a selector value
// switch <numval> { stmt0; stmt1;...;stmtN }
// numval < 0: treated as numval == 0
// numval > N: treated as numval == N
//
numvar getswitchstatement(void) {
numvar thesymval = symval;
//char *fetchmark;
numvar fetchmark;
numvar retval = 0;
byte thesym = sym;
getsym(); // eat "switch"
getnum(); // evaluate the switch selector
if (expval < 0) expval = 0; // map negative values to zero
byte which = (byte) expval; // and stash it for reference
if (sym != s_lcurly) expectedchar('{');
getsym(); // eat "{"
// we sit before the first statement
// scan and discard the <selector>'s worth of statements
// that sit before the one we want
while ((which > 0) && (sym != s_eof) && (sym != s_rcurly)) {
//fetchmark = fetchptr;
fetchmark = markparsepoint();
thesym = sym;
thesymval = symval;
skipstatement();
if ((sym != s_eof) && (sym != s_rcurly)) --which;
}
// If the selector is greater than the number of statements,
// back up and execute the last one
if (which > 0) { // oops ran out of piddys
//fetchptr = fetchmark; // restore to last statement
//primec(); // set up for getsym()
returntoparsepoint(fetchmark, 0);
sym = thesym;
symval = thesymval;
}
//unexpected(M_number);
// execute the statement we're pointing at
retval = getstatement();
// eat the rest of the statement block to "}"
while ((sym != s_eof) && (sym != s_rcurly)) skipstatement();
if (sym == s_rcurly) getsym(); // eat "}"
return retval;
}
// Get a statement
void getstatement(void) {
#if !defined(TINY85)
chkbreak();
#endif
if (sym == s_while) {
// at this point sym is pointing at s_while, before the conditional expression
// save fetchptr so we can restart parsing from here as the while iterates
char *fetchmark = fetchptr;
for (;;) {
fetchptr = fetchmark; // restore to mark
primec(); // set up for mr. getsym()
getsym(); // fetch the start of the conditional
if (!getnum()) {
//longjmp(env, X_EXIT); // get the conditional; exit on false
sym = s_eof; // we're finished here. move along.
return;
}
if (sym != s_colon) expectedchar(':');
getsym(); // eat :
getstatementlist();
}
}
else if (sym == s_if) {
getsym(); // fetch the start of the conditional
if (!getnum()) {
//longjmp(env, X_EXIT); // get the conditional; exit on false
sym = s_eof;
return;
}
if (sym != s_colon) expectedchar(':');
getsym(); // eat :
getstatementlist();
}
#if SKETCH
// The switch statement: call one of N macros based on a selector value
// switch <numval>: macroid1, macroid2,.., macroidN
// numval < 0: numval = 0
// numval > N: numval = N
else if (sym == s_switch) {
getsym(); // eat "switch"
numvar selector = getnum(); // evaluate the switch value
if (selector < 0) selector = 0;
if (sym != s_colon) expectedchar(':');
// we sit before the first macroid
// scan and discard the <selector>'s worth of macro ids
// that sit before the one we want
for (;;) {
getsym(); // get an id, sets symval to its eeprom addr as a side effect
if (sym != s_macro) expected (6); // TODO: define M_macro instead of 6
getsym(); // eat id, get separator; assume symval is untouched
if ((sym == s_semi) || (sym == s_eof)) break; // last case is default so we exit always
if (sym != s_comma) expectedchar(',');
if (!selector) break; // ok, this is the one we want to execute
selector--; // one down...
}
// call the macro whose addr is squirreled in symval all this time
// on return, the parser is ready to pick up where we left off
doMacroCall(symval);
// scan past the rest of the unused switch options, if any
// TODO: syntax checking for non-chosen options could be made much tighter at the cost of some space
while ((sym != s_semi) && (sym != s_eof)) getsym(); // scan to end of statement without executing
}
#endif
else if ((sym == s_macro) || (sym == s_undef)) { // macro def or ref
getsym(); // scan past macro name to next symbol: ; or :=
if (sym == s_define) { // macro definition: macroid := strvalue
// to define the macro, we need to copy the id somewhere on the stack
// to avoid having this local buffer in every getstatement stack frame,
// we break out defineMacro here to a separate function that only eats that
// stack in the case that a macro is being defined
#ifdef TINY85
unexpected(M_defmacro);
#else
defineMacro();
#endif
}
else if ((sym == s_semi) || (sym == s_eof)) { // valid macro reference: let's call it
#if SKETCH
doMacroCall(symval); // parseid stashes the macro address in symval
#else
char op = sym; // save sym for restore
expval = findKey(idbuf); // assumes id in idbuf isn't clobbered since getsym() above
if (expval >= 0) {
char *fetchmark = fetchptr; // save the current parse pointer
// call the macro
calleeprommacro(findend(expval)); // register the macro into the parser stream
getsym();
getstatementlist(); // parse and execute the macro code here
if (sym != s_eof) expected(M_eof);
// restore parsing context so we can resume cleanly
fetchptr = fetchmark; // restore pointer
primec(); // and inchar
sym = op; // restore saved sym: s_semi or s_eof
} else unexpected(M_id);
#endif
}
else expectedchar(';');
//else getexpression(); // assume it was macro1+32+macro2...
}
else if (sym == s_run) { // run macroname
getsym();
if (sym != s_macro) unexpected(M_id);
#if 0
// address of macroid is in symval via parseid
startTask(kludge(symval));
getsym();
#else
// address of macroid is in symval via parseid
// check for [,snoozeintervalms]
getsym(); // eat macroid to check for comma; symval untouched
if (sym == s_comma) {
vpush(symval);
getsym(); // eat the comma
getnum(); // get a number or else
startTask(kludge(vpop()), expval);
}
else startTask(kludge(symval), 0);
#endif
}
else if (sym == s_stop) {
getsym();
if (sym == s_mul) { // stop * stops all tasks
initTaskList();
getsym();
}
else if ((sym == s_semi) || (sym == s_eof)) {
if (background) stopTask(curtask); // stop with no args stops the current task IF we're in back
else initTaskList(); // in foreground, stop all
}
else stopTask(getnum());
}
else if (sym == s_boot) reboot();
#if !defined(TINY85)
else if (sym == s_rm) { // rm "sym" or rm *
getsym();
if (sym == s_macro) {
eraseentry(idbuf);
}
else if (sym == s_mul) nukeeeprom();
else expected(M_id);
getsym();
}
else if (sym == s_ps) showTaskList();
else if (sym == s_peep) { getsym(); cmd_peep(); }
else if (sym == s_ls) { getsym(); cmd_ls(); }
else if (sym == s_help) { getsym(); cmd_help(); }
else if (sym == s_print) { getsym(); cmd_print(); }
#endif
#ifdef HEX_UPLOAD
// a line beginning with a colon is treated as a hex record
// containing data to upload to eeprom
//
// TODO: verify checksum
//
else if (sym == s_colon) {
// fetchptr points at the byte count
byte byteCount = gethex(2); // 2 bytes byte count
int addr = gethex(4); // 4 bytes address
byte recordType = gethex(2); // 2 bytes record type; now fetchptr -> data
if (recordType == 1) reboot(); // reboot on EOF record (01)
if (recordType != 0) return; // we only handle the data record (00)
if (addr == 0) nukeeeprom(); // auto-clear eeprom on write to 0000
while (byteCount--) eewrite(addr++, gethex(2)); // update the eeprom
gethex(2); // discard the checksum
getsym(); // and re-prime the parser
}
#endif
else {
getexpression();
}
}
//
// Recursive descent parser, old-school style.
//
void getfactor(void) {
numvar thesymval = symval;
byte thesym = sym;
getsym(); // eat the sym we just saved
switch (thesym) {
case s_nval:
vpush(thesymval);
break;
case s_nvar:
if (sym == s_equals) { // assignment, push is after the break;
getsym();
assignVar(thesymval, getnum());
}
else if (sym == s_incr) { // postincrement nvar++
vpush(getVar(thesymval));
assignVar(thesymval, getVar(thesymval) + 1);
getsym();
break;
}
else if (sym == s_decr) { // postdecrement nvar--
vpush(getVar(thesymval));
assignVar(thesymval, getVar(thesymval) - 1);
getsym();
break;
}
vpush(getVar(thesymval)); // both assignment and reference get pushed here
break;
case s_nfunct:
dofunctioncall(thesymval); // get its value onto the stack
break;
// Script-function-returning-value used as a factor
case s_script_eeprom: // macro returning value
callscriptfunction(SCRIPT_EEPROM, findend(thesymval));
break;
case s_script_progmem:
callscriptfunction(SCRIPT_PROGMEM, thesymval);
break;
case s_script_file:
callscriptfunction(SCRIPT_FILE, (numvar) 0); // name implicitly in idbuf!
break;
case s_apin: // analog pin reference like a0
if (sym == s_equals) { // digitalWrite or analogWrite
getsym();
analogWrite(thesymval, getnum());
vpush(expval);
}
else vpush(analogRead(thesymval));
break;
case s_dpin: // digital pin reference like d1
if (sym == s_equals) { // digitalWrite or analogWrite
getsym();
digitalWrite(thesymval, getnum());
vpush(expval);
}
else vpush(digitalRead(thesymval));
break;
case s_incr:
if (sym != s_nvar) expected(M_var);
assignVar(symval, getVar(symval) + 1);
vpush(getVar(symval));
getsym();
break;
case s_decr: // pre decrement
if (sym != s_nvar) expected(M_var);
assignVar(symval, getVar(symval) - 1);
vpush(getVar(symval));
getsym();
break;
case s_arg: // arg(n) - argument value
if (sym != s_lparen) expectedchar(s_lparen);
getsym(); // eat '('
vpush(getarg(getnum()));
if (sym != s_rparen) expectedchar(s_rparen);
getsym(); // eat ')'
break;
case s_lparen: // expression in parens
getexpression();
if (exptype != s_nval) expected(M_number);
if (sym != s_rparen) missing(M_rparen);
vpush(expval);
getsym(); // eat the )
break;
//
// The Family of Unary Operators, which Bind Most Closely to their Factor
//
case s_add: // unary plus (like +3) is kind of a no-op
getfactor(); // scan a factor and leave its result on the stack
break; // done
case s_sub: // unary minus (like -3)
getfactor();
vpush(-vpop()); // similar to above but we adjust the stack value
break;
case s_bitnot:
getfactor();
vpush(~vpop());
break;
case s_logicalnot:
getfactor();
vpush(!vpop());
break;
case s_bitand: // &var gives address-of-var; ¯o gives eeprom address of macro
if (sym == s_nvar) vpush((numvar) &vars[symval]);
else if (sym == s_script_eeprom) vpush(symval);
else expected(M_var);
getsym(); // eat the var reference
break;
case s_mul: // *foo is contents-of-address-foo; *foo=bar is byte poke assignment
/*****
// what is really acceptable for an lvalue here? ;)
// *y = 5 is failing now by assigning 5 to y before the * is dereferenced
// due to calling getfactor
// everything else works :(
*****/
getfactor();
#if 0
if (sym == s_equals) {
getsym(); // eat '='
getexpression();
* (volatile byte *) vpop() = (byte) expval;
vpush((numvar) (byte) expval);
}
else
#endif
vpush((numvar) (* (volatile byte *) vpop()));
break;
default:
unexpected(M_number);
}
}
// Get a statement
numvar getstatement(void) {
numvar retval = 0;
char *fetchmark;
chkbreak();
//#define LINEMODE
#ifdef LINEMODE
if (sym == s_while) {
// at this point sym is pointing at s_while, before the conditional expression
// save fetchptr so we can restart parsing from here as the while iterates
char *fetchmark = fetchptr;
for (;;) {
fetchptr = fetchmark; // restore to mark
primec(); // set up for mr. getsym()
getsym(); // fetch the start of the conditional
if (!getnum()) {
//longjmp(env, X_EXIT); // get the conditional; exit on false
sym = s_eof; // we're finished here. move along.
return;
}
if (sym != s_colon) expectedchar(':');
getsym(); // eat :
getstatementlist();
}
}
else if (sym == s_if) {
getsym(); // fetch the start of the conditional
if (!getnum()) {
//longjmp(env, X_EXIT); // get the conditional; exit on false
sym = s_eof;
return;
}
if (sym != s_colon) expectedchar(':');
getsym(); // eat :
getstatementlist();
}
// The switch statement: call one of N macros based on a selector value
// switch <numval>: macroid1, macroid2,.., macroidN
// numval < 0: numval = 0
// numval > N: numval = N
else if (sym == s_switch) {
getsym(); // eat "switch"
numvar selector = getnum(); // evaluate the switch value
if (selector < 0) selector = 0;
if (sym != s_colon) expectedchar(':');
// we sit before the first macroid
// scan and discard the <selector>'s worth of macro ids
// that sit before the one we want
for (;;) {
getsym(); // get an id, sets symval to its eeprom addr as a side effect
if (sym != s_macro) expected (6); // TODO: define M_macro instead of 6
getsym(); // eat id, get separator; assume symval is untouched
if ((sym == s_semi) || (sym == s_eof)) break; // last case is default so we exit always
if (sym != s_comma) expectedchar(',');
if (!selector) break; // ok, this is the one we want to execute
selector--; // one down...
}
// call the macro whose addr is squirreled in symval all this time
// on return, the parser is ready to pick up where we left off
domacrocall(symval);
// scan past the rest of the unused switch options, if any
// TODO: syntax checking for non-chosen options could be made much tighter at the cost of some space
while ((sym != s_semi) && (sym != s_eof)) getsym(); // scan to end of statement without executing
}
#else
// new statement handling
if (sym == s_while) {
// at this point sym is pointing at s_while, before the conditional expression
// save fetchptr so we can restart parsing from here as the while iterates
fetchmark = fetchptr;
for (;;) {
fetchptr = fetchmark; // restore to mark
primec(); // set up for mr. getsym()
getsym(); // fetch the start of the conditional
if (getnum()) {
retval = getstatement();
if (sym == s_returning) break; // exit if we caught a return
}
else {
skipstatement();
break;
}
}
}
else if (sym == s_if) {
getsym(); // eat "if"
if (getnum()) {
retval = getstatement();
if (sym == s_else) {
getsym(); // eat "else"
skipstatement();
}
} else {
skipstatement();
if (sym == s_else) {
getsym(); // eat "else"
retval = getstatement();
}
}
}
else if (sym == s_lcurly) {
getsym(); // eat "{"
while ((sym != s_eof) && (sym != s_returning) && (sym != s_rcurly)) retval = getstatement();
if (sym == s_rcurly) getsym(); // eat "}"
}
else if (sym == s_return) {
getsym(); // eat "return"
if ((sym != s_eof) && (sym != s_semi)) retval = getnum();
sym = s_returning; // signal we're returning up the line
}
else if (sym == s_switch) retval = getswitchstatement();
else if (sym == s_function) cmd_function();
#endif
else if (sym == s_run) { // run macroname
getsym();
if (sym != s_macro) unexpected(M_id);
// address of macroid is in symval via parseid
// check for [,snoozeintervalms]
getsym(); // eat macroid to check for comma; symval untouched
if (sym == s_comma) {
vpush(symval);
getsym(); // eat the comma
getnum(); // get a number or else
startTask(kludge(vpop()), expval);
}
else startTask(kludge(symval), 0);
}
else if (sym == s_stop) {
getsym();
if (sym == s_mul) { // stop * stops all tasks
initTaskList();
getsym();
}
else if ((sym == s_semi) || (sym == s_eof)) {
if (background) stopTask(curtask); // stop with no args stops the current task IF we're in back
else initTaskList(); // in foreground, stop all
}
else stopTask(getnum());
}
else if (sym == s_boot) reboot();
#if !defined(TINY85)
else if (sym == s_rm) { // rm "sym" or rm *
getsym();
if (sym == s_macro) {
eraseentry(idbuf);
}
else if (sym == s_mul) nukeeeprom();
else if (sym != s_undef) expected(M_id);
getsym();
}
else if (sym == s_ps) { getsym(); showTaskList(); }
else if (sym == s_peep) { getsym(); cmd_peep(); }
else if (sym == s_ls) { getsym(); cmd_ls(); }
else if (sym == s_help) { getsym(); cmd_help(); }
else if (sym == s_print) { getsym(); cmd_print(); }
else if (sym == s_semi) { ; } // ;)
#endif
#ifdef HEX_UPLOAD
// a line beginning with a colon is treated as a hex record
// containing data to upload to eeprom
//
// TODO: verify checksum
//
else if (sym == s_colon) {
// fetchptr points at the byte count
byte byteCount = gethex(2); // 2 bytes byte count
int addr = gethex(4); // 4 bytes address
byte recordType = gethex(2); // 2 bytes record type; now fetchptr -> data
if (recordType == 1) reboot(); // reboot on EOF record (01)
if (recordType != 0) return; // we only handle the data record (00)
if (addr == 0) nukeeeprom(); // auto-clear eeprom on write to 0000
while (byteCount--) eewrite(addr++, gethex(2)); // update the eeprom
gethex(2); // discard the checksum
getsym(); // and re-prime the parser
}
#endif
else getexpression();
if (sym == s_semi) getsym(); // eat trailing ';'
return retval;
}