The Battle for Wesnoth  1.17.0-dev
lapi.h
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1 /*
2 ** $Id: lapi.h $
3 ** Auxiliary functions from Lua API
4 ** See Copyright Notice in lua.h
5 */
6 
7 #ifndef lapi_h
8 #define lapi_h
9 
10 
11 #include "llimits.h"
12 #include "lstate.h"
13 
14 
15 /* Increments 'L->top', checking for stack overflows */
16 #define api_incr_top(L) {L->top++; api_check(L, L->top <= L->ci->top, \
17  "stack overflow");}
18 
19 
20 /*
21 ** If a call returns too many multiple returns, the callee may not have
22 ** stack space to accommodate all results. In this case, this macro
23 ** increases its stack space ('L->ci->top').
24 */
25 #define adjustresults(L,nres) \
26  { if ((nres) <= LUA_MULTRET && L->ci->top < L->top) L->ci->top = L->top; }
27 
28 
29 /* Ensure the stack has at least 'n' elements */
30 #define api_checknelems(L,n) api_check(L, (n) < (L->top - L->ci->func), \
31  "not enough elements in the stack")
32 
33 
34 /*
35 ** To reduce the overhead of returning from C functions, the presence of
36 ** to-be-closed variables in these functions is coded in the CallInfo's
37 ** field 'nresults', in a way that functions with no to-be-closed variables
38 ** with zero, one, or "all" wanted results have no overhead. Functions
39 ** with other number of wanted results, as well as functions with
40 ** variables to be closed, have an extra check.
41 */
42 
43 #define hastocloseCfunc(n) ((n) < LUA_MULTRET)
44 
45 #define codeNresults(n) (-(n) - 3)
46 
47 #endif