[FFmpeg-devel] [PATCHv2 1/3] avutil/eval: separate AVExpr state to a new AVExprState struct
Marton Balint
cus at passwd.hu
Fri Jan 10 01:49:08 EET 2020
On Thu, 9 Jan 2020, Michael Niedermayer wrote:
> On Wed, Jan 01, 2020 at 05:40:33PM +0100, Marton Balint wrote:
>>
>>
>> On Wed, 1 Jan 2020, Michael Niedermayer wrote:
>>
>>> On Mon, Dec 30, 2019 at 11:23:40PM +0100, Marton Balint wrote:
>>>> Also add helper functions to allocate and free such a struct, and make it
>>>> usable by providing a new av_eval_expr2 function for which you can specify a
>>>> custom AVExprState.
>>>>
>>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>>>> ---
>>>> doc/APIchanges | 4 ++++
>>>> libavutil/eval.c | 36 +++++++++++++++++++++++++-----------
>>>> libavutil/eval.h | 41 +++++++++++++++++++++++++++++++++++++++++
>>>> libavutil/version.h | 2 +-
>>>> 4 files changed, 71 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/doc/APIchanges b/doc/APIchanges
>>>> index 3c24dc6fbc..d0b33bda02 100644
>>>> --- a/doc/APIchanges
>>>> +++ b/doc/APIchanges
>>>> @@ -15,6 +15,10 @@ libavutil: 2017-10-21
>>>>
>>>> API changes, most recent first:
>>>>
>>>> +2020-01-xx - xxxxxxxxxx - lavu 56.39.100 - eval.h
>>>> + Add AVExprState struct and av_expr_eval2, av_expr_state_alloc,
>>>> + av_expr_state_free functions
>>>> +
>>>> 2019-12-27 - xxxxxxxxxx - lavu 56.38.100 - eval.h
>>>> Add av_expr_count_func().
>>>>
>>>> diff --git a/libavutil/eval.c b/libavutil/eval.c
>>>> index d527f6a9d0..4619d0fba0 100644
>>>> --- a/libavutil/eval.c
>>>> +++ b/libavutil/eval.c
>>>> @@ -53,7 +53,6 @@ typedef struct Parser {
>>>> void *opaque;
>>>> int log_offset;
>>>> void *log_ctx;
>>>> -#define VARS 10
>>>> double *var;
>>>> } Parser;
>>>>
>>>> @@ -173,7 +172,7 @@ struct AVExpr {
>>>> double (*func2)(void *, double, double);
>>>> } a;
>>>> struct AVExpr *param[3];
>>>> - double *var;
>>>> + AVExprState *state;
>>>> };
>>>>
>>>> static double etime(double v)
>>>> @@ -191,7 +190,7 @@ static double eval_expr(Parser *p, AVExpr *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[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
>>>> + case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, AV_EXPR_STATE_NB_VARS-1)];
>>>> case e_isnan: return e->value * !!isnan(eval_expr(p, e->param[0]));
>>>> case e_isinf: return e->value * !!isinf(eval_expr(p, e->param[0]));
>>>> case e_floor: return e->value * floor(eval_expr(p, e->param[0]));
>>>> @@ -230,7 +229,7 @@ static double eval_expr(Parser *p, AVExpr *e)
>>>> return x;
>>>> }
>>>> case e_random:{
>>>> - int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1);
>>>> + int idx= av_clip(eval_expr(p, e->param[0]), 0, AV_EXPR_STATE_NB_VARS-1);
>>>> uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx];
>>>> r= r*1664525+1013904223;
>>>> p->var[idx]= r;
>>>> @@ -245,7 +244,7 @@ static double eval_expr(Parser *p, AVExpr *e)
>>>> case e_taylor: {
>>>> double t = 1, d = 0, v;
>>>> double x = eval_expr(p, e->param[1]);
>>>> - int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, VARS-1) : 0;
>>>> + int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, AV_EXPR_STATE_NB_VARS-1) : 0;
>>>> int i;
>>>> double var0 = p->var[id];
>>>> for(i=0; i<1000; i++) {
>>>> @@ -320,7 +319,7 @@ static double eval_expr(Parser *p, AVExpr *e)
>>>> case e_div: return e->value * ((!CONFIG_FTRAPV || d2 ) ? (d / d2) : d * INFINITY);
>>>> case e_add: return e->value * (d + d2);
>>>> case e_last:return e->value * d2;
>>>> - case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
>>>> + case e_st : return e->value * (p->var[av_clip(d, 0, AV_EXPR_STATE_NB_VARS-1)]= d2);
>>>> case e_hypot:return e->value * hypot(d, d2);
>>>> case e_atan2:return e->value * atan2(d, d2);
>>>> case e_bitand: return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d & (long int)d2);
>>>> @@ -333,13 +332,23 @@ static double eval_expr(Parser *p, AVExpr *e)
>>>>
>>>> static int parse_expr(AVExpr **e, Parser *p);
>>>>
>>>> +AVExprState *av_expr_state_alloc(void)
>>>> +{
>>>> + return av_mallocz(sizeof(AVExprState));
>>>> +}
>>>> +
>>>> +void av_expr_state_free(AVExprState **ps)
>>>> +{
>>>> + av_freep(ps);
>>>> +}
>>>> +
>>>> void av_expr_free(AVExpr *e)
>>>> {
>>>> if (!e) return;
>>>> av_expr_free(e->param[0]);
>>>> av_expr_free(e->param[1]);
>>>> av_expr_free(e->param[2]);
>>>> - av_freep(&e->var);
>>>> + av_expr_state_free(&e->state);
>>>> av_freep(&e);
>>>> }
>>>>
>>>> @@ -724,8 +733,8 @@ int av_expr_parse(AVExpr **expr, const char *s,
>>>> ret = AVERROR(EINVAL);
>>>> goto end;
>>>> }
>>>> - e->var= av_mallocz(sizeof(double) *VARS);
>>>> - if (!e->var) {
>>>> + e->state = av_expr_state_alloc();
>>>> + if (!e->state) {
>>>> ret = AVERROR(ENOMEM);
>>>> goto end;
>>>> }
>>>> @@ -763,16 +772,21 @@ int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg)
>>>> return expr_count(e, counter, size, ((int[]){e_const, e_func1, e_func2})[arg]);
>>>> }
>>>>
>>>> -double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
>>>> +double av_expr_eval2(AVExpr *e, AVExprState *s, const double *const_values, void *opaque)
>>>> {
>>>> Parser p = { 0 };
>>>> - p.var= e->var;
>>>> + p.var = s ? s->vars : e->state->vars;
>>>>
>>>> p.const_values = const_values;
>>>> p.opaque = opaque;
>>>> return eval_expr(&p, e);
>>>> }
>>>>
>>>> +double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
>>>> +{
>>>> + return av_expr_eval2(e, NULL, const_values, opaque);
>>>> +}
>>>> +
>>>> int av_expr_parse_and_eval(double *d, const char *s,
>>>> const char * const *const_names, const double *const_values,
>>>> const char * const *func1_names, double (* const *funcs1)(void *, double),
>>>> diff --git a/libavutil/eval.h b/libavutil/eval.h
>>>> index 068c62cdab..d5b34e54e8 100644
>>>> --- a/libavutil/eval.h
>>>> +++ b/libavutil/eval.h
>>>> @@ -30,6 +30,21 @@
>>>>
>>>> typedef struct AVExpr AVExpr;
>>>>
>>>> +/**
>>>> + * This structure stores a state used by the expression evaluator.
>>>> + * It must be allocated and freed with its proper allocation functions.
>>>> + *
>>>> + * @see av_expr_state_alloc()
>>>> + * @see av_expr_state_free()
>>>> + */
>>>> +typedef struct AVExprState {
>>>
>>>> +#define AV_EXPR_STATE_NB_VARS 10
>>>
>>> This would make the NB_VARS part of the public API and it would
>>> not be changeable easily, theres nothing here that says it cannot be used
>>> by the user
>>
>> I assumed it is OK as long as you only increase this. If you are adding
>> other fields, then you are of course locked to 10 vars. What do you propose
>> instead?
>
> Well, AV_EXPR_STATE_NB_VARS should not be a value in a public header
> which does not contain a comment saying that it must not be used outside
> libavutil
My intention was that it _is_ public, because it lets the user know the
length (or rather the minimum length) of the variable array. The user
could just as easily use FF_ARRAY_ELEMS(AVExprState->vars).
>
> also the question is, can this struct be made opaque for the user ?
> if so we can change it in any way in the future, including making it
> non opaque if needed
Well, in v1 the struct was opaque but you wanted to be able
to initialize the state and I preferred a non-opaque struct to do that
instead of a parameter list in _alloc().
I can revert to v1, but I still think using _alloc() is not the way to
initialize state. How do you want me to proceed?
Thanks,
Marton
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