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support seperating expressons by ; 

support variables, the syntax isnt beautifull (st(a,b) means var[a]=b and ld(a) var[a]) but for a mere 19 lines of code its fairly simple, if anyone wants to write real variables support with names for variables and = and [] then that would of course be welcome but only if it doesnt bloat the code up terribly...)

Originally committed as revision 6813 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2006-10-27 22:16:25 +00:00
parent 418f17e006
commit 835954e3a4
1 changed files with 23 additions and 4 deletions
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27
libavcodec/eval.c
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@ -56,6 +56,8 @@ typedef struct Parser{
char **func2_name; // NULL terminated
void *opaque;
char **error;
#define VARS 10
double var[VARS];
} Parser;
static int8_t si_prefixes['z' - 'E' + 1]={
@ -128,9 +130,10 @@ static int strmatch(const char *s, const char *prefix){
struct ff_expr_s {
enum {
e_value, e_const, e_func0, e_func1, e_func2,
e_squish, e_gauss,
e_squish, e_gauss, e_ld,
e_mod, e_max, e_min, e_eq, e_gt, e_gte,
e_pow, e_mul, e_div, e_add,
e_last, e_st,
} type;
double value; // is sign in other types
union {
@ -151,6 +154,7 @@ static double eval_expr(Parser * p, AVEvalExpr * e) {
case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
case e_ld: return e->value * p->var[clip(eval_expr(p, e->param[0]), 0, VARS-1)];
default: {
double d = eval_expr(p, e->param[0]);
double d2 = eval_expr(p, e->param[1]);
@ -165,6 +169,8 @@ static double eval_expr(Parser * p, AVEvalExpr * e) {
case e_mul: return e->value * (d * d2);
case e_div: return e->value * (d / d2);
case e_add: return e->value * (d + d2);
case e_last:return d2;
case e_st : return e->value * (p->var[clip(d, 0, VARS-1)]= d2);
}
}
}
@ -258,6 +264,8 @@ static AVEvalExpr * parse_primary(Parser *p) {
else if( strmatch(next, "gt" ) ) d->type = e_gt;
else if( strmatch(next, "lte" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
else if( strmatch(next, "lt" ) ) { AVEvalExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
else if( strmatch(next, "ld" ) ) d->type = e_ld;
else if( strmatch(next, "st" ) ) d->type = e_st;
else {
for(i=0; p->func1_name && p->func1_name[i]; i++){
if(strmatch(next, p->func1_name[i])){
@ -319,6 +327,15 @@ static AVEvalExpr * parse_term(Parser *p){
return e;
}
static AVEvalExpr * parse_subexpr(Parser *p) {
AVEvalExpr * e = parse_term(p);
while(*p->s == '+' || *p->s == '-') {
e= new_eval_expr(e_add, 1, e, parse_term(p));
};
return e;
}
static AVEvalExpr * parse_expr(Parser *p) {
AVEvalExpr * e;
@ -326,10 +343,11 @@ static AVEvalExpr * parse_expr(Parser *p) {
return NULL;
p->stack_index--;
e = parse_term(p);
e = parse_subexpr(p);
while(*p->s == '+' || *p->s == '-') {
e= new_eval_expr(e_add, 1, e, parse_term(p));
while(*p->s == ';') {
p->s++;
e= new_eval_expr(e_last, 1, e, parse_subexpr(p));
};
p->stack_index++;
@ -345,6 +363,7 @@ static int verify_expr(AVEvalExpr * e) {
case e_func0:
case e_func1:
case e_squish:
case e_ld:
case e_gauss: return verify_expr(e->param[0]);
default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
}