void exec_for()
{
int cond;
char *temp, *temp2;
int brace ;
get_token();
eval_exp(&cond);
if(*token!=';')
sntx_err(SEMI_EXPECTED);
prog++;
temp = prog;
for(;;) {
eval_exp(&cond);
if(*token!=';')
sntx_err(SEMI_EXPECTED);
prog++;
temp2 = prog;
brace = 1;
while(brace) {
get_token();
if(*token=='(') brace++;
if(*token==')') brace--;
}
if(cond)
interp_block();
else {
find_eob();
return;
}
prog = temp2;
eval_exp(&cond);
prog = temp;
}
}
/* Execute a for loop. */
void exec_for(void)
{
int cond;
char *temp, *temp2;
int brace ;
get_token();
eval_exp(&cond); /* initialization expression */
if(*token != ';') sntx_err(SEMI_EXPECTED);
prog++; /* get past the ; */
temp = prog;
for(;;) {
eval_exp(&cond); /* check the condition */
if(*token != ';') sntx_err(SEMI_EXPECTED);
prog++; /* get past the ; */
temp2 = prog;
/* find the start of the for block */
brace = 1;
while(brace) {
get_token();
if(*token == '(') brace++;
if(*token == ')') brace--;
}
if(cond) interp_block(); /* if true, interpret */
else { /* otherwise, skip around loop */
find_eob();
return;
}
prog = temp2;
eval_exp(&cond); /* do the increment */
prog = temp; /* loop back to top */
}
}
/* Interpret a single statement or block of code. When
interp_block() returns from its initial call, the final
brace (or a return) in main() has been encountered.
*/
void interp_block(void)
{
int value;
char block = 0;
do {
token_type = get_token();
/* If interpreting single statement, return on
first semicolon.
*/
/* see what kind of token is up */
if(token_type == IDENTIFIER) {
/* Not a keyword, so process expression. */
putback(); /* restore token to input stream for
further processing by eval_exp() */
eval_exp(&value); /* process the expression */
if(*token!=';') sntx_err(SEMI_EXPECTED);
}
else if(token_type==BLOCK) { /* if block delimiter */
if(*token == '{') /* is a block */
block = 1; /* interpreting block, not statement */
else return; /* is a }, so return */
}
else /* is keyword */
switch(tok) {
case CHAR:
case INT: /* declare local variables */
putback();
decl_local();
break;
case RETURN: /* return from function call */
func_ret();
return;
case IF: /* process an if statement */
exec_if();
break;
case ELSE: /* process an else statement */
find_eob(); /* find end of else block
and continue execution */
break;
case WHILE: /* process a while loop */
exec_while();
break;
case DO: /* process a do-while loop */
exec_do();
break;
case FOR: /* process a for loop */
exec_for();
break;
case END:
exit(0);
}
} while (tok != FINISHED && block);
}
void jpeg_encode_block(short *in, short *last_block, uint8_t **out, int *out_length, int quality)
{
const int bwidth = 8;
const int bheight = 8;
short zz[64];
dc_shift_short(in, bwidth, bheight, -128);
dct_8x8(in);
quant_8x8(in, quality);
zigzag_8x8(in, zz);
int zz_len = find_eob(zz);
huffman_enc_64(zz, zz_len, out, out_length, last_block);
}
/* Execute a while loop. */
void exec_while(void)
{
int cond;
char *temp;
putback();
temp = prog; /* save location of top of while loop */
get_token();
eval_exp(&cond); /* check the conditional expression */
if(cond) interp_block(); /* if true, interpret */
else { /* otherwise, skip around loop */
find_eob();
return;
}
prog = temp; /* loop back to top */
}
void exec_while()
{
int cond;
char *temp;
putback();
temp = prog;
get_token();
eval_exp(&cond);
if(cond)
interp_block();
else {
find_eob();
return;
}
prog = temp;
}
void exec_if()
{
int cond;
eval_exp(&cond);
if(cond) {
interp_block();
} else {
find_eob();
get_token();
if(tok!=ELSE) {
putback();
return;
}
interp_block();
}
}
void interp_block()
{
int value;
char block = 0;
do {
token_type = get_token();
if(token_type==IDENTIFIER) {
putback();
eval_exp(&value);
if(*token!=';') sntx_err(SEMI_EXPECTED);
}
else if(token_type==BLOCK) {
if(*token=='{')
block = 1;
else
return;
}
else switch(tok) {
case CHAR:
case INT:
putback();
decl_local();
break;
case RETURN:
func_ret();
return;
case IF:
exec_if();
break;
case ELSE:
find_eob();
break;
case WHILE:
exec_while();
break;
case DO:
exec_do();
break;
case FOR: exec_for();
break;
case END:
return;
}
} while (tok != FINISHED && block);
}
/* Execute an if statement. */
void exec_if(void)
{
int cond;
eval_exp(&cond); /* get if expression */
if(cond) { /* is true so process target of IF */
interp_block();
}
else { /* otherwise skip around IF block and
process the ELSE, if present */
find_eob(); /* find start of next line */
get_token();
if(tok != ELSE) {
putback(); /* restore token if
no ELSE is present */
return;
}
interp_block();
}
}
