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 /* Map [-1, inf) (range of 'nresults') into (-inf, -2] */ 46 #define codeNresults(n) (-(n) - 3) 47 #define decodeNresults(n) (-(n) - 3) 48 49 #endif 50