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conf: add possibility to evaluate simple integer math expressions

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It is useful to use the math expressions for the values in configuration.
This patch adds a simple expression evaluation routines (integer only).
The syntax is simplified unix shell (bash) style.

Examples:

	$[1 + 1]
	$[$[2 + 2] / $var1]
	$[0xa0 | 0x05]

As a bonus, the variable substitutions were more abstracted.
The function snd_config_expand_custom() was introduced to be used
for example in the topology pre-precessor.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2021-11-29 14:57:29 +01:00
parent 32d332b786
commit bf528b9066
5 changed files with 389 additions and 18 deletions
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88
src/conf.c
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@ -318,6 +318,15 @@ Arguments are referred to with a dollar-sign ($) and the name of the argument:
card $CARD
\endcode
\section confarg_math simple math expressions
The simple math expressions are identified using a unix shell like expression syntax
with a dollar-sign ($) and bracket ([):
\code
card "$[$CARD + 1]"
\endcode
\section confarg_usage Usage
To use a block with arguments, write the argument values after the key,
@ -355,6 +364,7 @@ pcm.demo {
}
\endcode
*/
/*! \page conffunc Runtime functions in configuration files
@ -4802,21 +4812,23 @@ typedef int (*snd_config_walk_callback_t)(snd_config_t *src,
snd_config_t *root,
snd_config_t **dst,
snd_config_walk_pass_t pass,
snd_config_t *private_data);
snd_config_expand_fcn_t fcn,
void *private_data);
#endif
static int snd_config_walk(snd_config_t *src,
snd_config_t *root,
snd_config_t **dst,
snd_config_walk_callback_t callback,
snd_config_t *private_data)
snd_config_expand_fcn_t fcn,
void *private_data)
{
int err;
snd_config_iterator_t i, next;
switch (snd_config_get_type(src)) {
case SND_CONFIG_TYPE_COMPOUND:
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_PRE, private_data);
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_PRE, fcn, private_data);
if (err <= 0)
return err;
snd_config_for_each(i, next, src) {
@ -4824,7 +4836,7 @@ static int snd_config_walk(snd_config_t *src,
snd_config_t *d = NULL;
err = snd_config_walk(s, root, (dst && *dst) ? &d : NULL,
callback, private_data);
callback, fcn, private_data);
if (err < 0)
goto _error;
if (err && d) {
@ -4833,7 +4845,7 @@ static int snd_config_walk(snd_config_t *src,
goto _error;
}
}
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_POST, private_data);
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_POST, fcn, private_data);
if (err <= 0) {
_error:
if (dst && *dst)
@ -4841,7 +4853,7 @@ static int snd_config_walk(snd_config_t *src,
}
break;
default:
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_LEAF, private_data);
err = callback(src, root, dst, SND_CONFIG_WALK_PASS_LEAF, fcn, private_data);
break;
}
return err;
@ -4851,7 +4863,8 @@ static int _snd_config_copy(snd_config_t *src,
snd_config_t *root ATTRIBUTE_UNUSED,
snd_config_t **dst,
snd_config_walk_pass_t pass,
snd_config_t *private_data ATTRIBUTE_UNUSED)
snd_config_expand_fcn_t fcn ATTRIBUTE_UNUSED,
void *private_data ATTRIBUTE_UNUSED)
{
int err;
const char *id = src->id;
@ -4932,14 +4945,23 @@ static int _snd_config_copy(snd_config_t *src,
int snd_config_copy(snd_config_t **dst,
snd_config_t *src)
{
return snd_config_walk(src, NULL, dst, _snd_config_copy, NULL);
return snd_config_walk(src, NULL, dst, _snd_config_copy, NULL, NULL);
}
static int _snd_config_expand_vars(snd_config_t **dst, const char *s, void *private_data)
{
snd_config_t *val, *vars = private_data;
if (snd_config_search(vars, s, &val) < 0)
return snd_config_make_string(dst, "");
return snd_config_copy(dst, val);
}
static int _snd_config_expand(snd_config_t *src,
snd_config_t *root ATTRIBUTE_UNUSED,
snd_config_t **dst,
snd_config_walk_pass_t pass,
snd_config_t *private_data)
snd_config_expand_fcn_t fcn,
void *private_data)
{
int err;
const char *id = src->id;
@ -4989,14 +5011,10 @@ static int _snd_config_expand(snd_config_t *src,
case SND_CONFIG_TYPE_STRING:
{
const char *s;
snd_config_t *val;
snd_config_t *vars = private_data;
snd_config_get_string(src, &s);
if (s && *s == '$') {
s++;
if (snd_config_search(vars, s, &val) < 0)
return 0;
err = snd_config_copy(dst, val);
err = snd_config_evaluate_string(dst, s, fcn, vars);
if (err < 0)
return err;
err = snd_config_set_id(*dst, id);
@ -5025,7 +5043,8 @@ static int _snd_config_evaluate(snd_config_t *src,
snd_config_t *root,
snd_config_t **dst ATTRIBUTE_UNUSED,
snd_config_walk_pass_t pass,
snd_config_t *private_data)
snd_config_expand_fcn_t fcn ATTRIBUTE_UNUSED,
void *private_data)
{
int err;
if (pass == SND_CONFIG_WALK_PASS_PRE) {
@ -5139,7 +5158,7 @@ int snd_config_evaluate(snd_config_t *config, snd_config_t *root,
{
/* FIXME: Only in place evaluation is currently implemented */
assert(result == NULL);
return snd_config_walk(config, root, result, _snd_config_evaluate, private_data);
return snd_config_walk(config, root, result, _snd_config_evaluate, NULL, private_data);
}
static int load_defaults(snd_config_t *subs, snd_config_t *defs)
@ -5539,6 +5558,41 @@ static int parse_args(snd_config_t *subs, const char *str, snd_config_t *defs)
return 0;
}
/**
* \brief Expands a configuration node, applying arguments and functions.
* \param[in] config Handle to the configuration node.
* \param[in] root Handle to the root configuration node.
* \param[in] fcn Custom function to obtain the referred variable name
* \param[in] private_data Private data node for the custom function
* \param[out] result The function puts the handle to the result
* configuration node at the address specified by
* \a result.
* \return A non-negative value if successful, otherwise a negative error code.
*
* If \a config has arguments (defined by a child with id \c \@args),
* this function replaces any string node beginning with $ with the
* respective argument value, or the default argument value, or nothing.
* Furthermore, any functions are evaluated (see #snd_config_evaluate).
* The resulting copy of \a config is returned in \a result.
*
* The new tree is not evaluated (\ref snd_config_evaluate).
*/
int snd_config_expand_custom(snd_config_t *config, snd_config_t *root,
snd_config_expand_fcn_t fcn, void *private_data,
snd_config_t **result)
{
snd_config_t *res;
int err;
err = snd_config_walk(config, root, &res, _snd_config_expand, fcn, private_data);
if (err < 0) {
SNDERR("Expand error (walk): %s", snd_strerror(err));
return err;
}
*result = res;
return 1;
}
/**
* \brief Expands a configuration node, applying arguments and functions.
* \param[in] config Handle to the configuration node.
@ -5589,7 +5643,7 @@ int snd_config_expand(snd_config_t *config, snd_config_t *root, const char *args
SNDERR("Args evaluate error: %s", snd_strerror(err));
goto _end;
}
err = snd_config_walk(config, root, &res, _snd_config_expand, subs);
err = snd_config_walk(config, root, &res, _snd_config_expand, _snd_config_expand_vars, subs);
if (err < 0) {
SNDERR("Expand error (walk): %s", snd_strerror(err));
goto _end;