1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
|
/* Should be a Lua module, roughly the same as test.lua
*/
/* NOTES -
From http://www.inf.puc-rio.br/~roberto/pil2/chapter15.pdf
"Well-behaved C libraries should export one function called
luaopen_modname, which is the function that require tries to call after
linking the library. In Section 26.2 we will discuss how to write C
libraries."
The "modname" bit is replaced by the name of the module. Though if the
module name includes a hyphen, the "require" function strips out the
hyphen and the bit before it.
Though it seems that chapter 26 is not in the same place?
http://www.lua.org/pil/26.2.html doesn't say much really, and is for
Lua 5.0
An example -
// build@ gcc -shared -I/home/sdonovan/lua/include -o mylib.so mylib.c
// includes for your code
#include <string.h>
#include <math.h>
// includes for Lua
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
// defining functions callable from Lua
static int l_createtable (lua_State *L) {
int narr = luaL_optint(L,1,0); // initial array slots, default 0
int nrec = luaL_optint(L,2,0); // intialof hash slots, default 0
lua_createtable(L,narr,nrec);
return 1;
}
static int l_solve (lua_State *L) {
double a = lua_tonumber(L,1); // coeff of x*x
double b = lua_tonumber(L,2); // coef of x
double c = lua_tonumber(L,3); // constant
double abc = b*b - 4*a*c;
if (abc < 0.0) {
lua_pushnil(L);
lua_pushstring(L,"imaginary roots!");
return 2;
} else {
abc = sqrt(abc);
a = 2*a;
lua_pushnumber(L,(-b + abc)/a);
lua_pushnumber(L,(+b - abc)/a);
return 2;
}
}
static const luaL_reg mylib[] = {
{"createtable",l_createtable},
{"solve",l_solve},
{NULL,NULL}
};
int luaopen_mylib(lua_State *L)
{
luaL_register (L, "mylib", mylib);
return 1;
}
*/
|
