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/*
basic.c - sample module
This module provides a simple `basic-sum' function.
I've used the following prefixes throughout the code:
- Sfoo: subr (function wraper)
- Qfoo: symbol value
- Ffoo: function value
*/
#include <emacs_module.h>
int plugin_is_GPL_compatible;
/* C function we want to expose to emacs */
static int64_t sum (int64_t a, int64_t b)
{
return a + b;
}
/* Proper module subr that wraps the C function */
static emacs_value Fsum (emacs_env *env, int nargs, emacs_value args[])
{
int64_t a = env->fixnum_to_int (env, args[0]);
int64_t b = env->fixnum_to_int (env, args[1]);
int64_t r = sum(a, b);
return env->make_fixnum (env, r);
}
/* Binds NAME to FUN */
static void bind_function (emacs_env *env, const char *name, emacs_value Ffun)
{
emacs_value Qfset = env->intern (env, "fset");
emacs_value Qsym = env->intern (env, name);
emacs_value args[] = { Qsym, Ffun };
env->funcall (env, Qfset, 2, args);
}
/* Provide FEATURE to Emacs */
static void provide (emacs_env *env, const char *feature)
{
emacs_value Qfeat = env->intern (env, feature);
emacs_value Qprovide = env->intern (env, "provide");
emacs_value args[] = { Qfeat };
env->funcall (env, Qprovide, 1, args);
}
int emacs_module_init (struct emacs_runtime *ert)
{
emacs_env *env = ert->get_environment (ert);
emacs_value Ssum = env->make_function (env, 2, 2, Fsum);
bind_function (env, "basic-sum", Ssum);
provide (env, "basic");
return 0;
}
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