18e3e3a7aSWarner Losh /* 20495ed39SKyle Evans ** $Id: lapi.h $ 38e3e3a7aSWarner Losh ** Auxiliary functions from Lua API 48e3e3a7aSWarner Losh ** See Copyright Notice in lua.h 58e3e3a7aSWarner Losh */ 68e3e3a7aSWarner Losh 78e3e3a7aSWarner Losh #ifndef lapi_h 88e3e3a7aSWarner Losh #define lapi_h 98e3e3a7aSWarner Losh 108e3e3a7aSWarner Losh 118e3e3a7aSWarner Losh #include "llimits.h" 128e3e3a7aSWarner Losh #include "lstate.h" 138e3e3a7aSWarner Losh 140495ed39SKyle Evans 15*a9490b81SWarner Losh /* Increments 'L->top.p', checking for stack overflows */ 16*a9490b81SWarner Losh #define api_incr_top(L) {L->top.p++; \ 17*a9490b81SWarner Losh api_check(L, L->top.p <= L->ci->top.p, \ 188e3e3a7aSWarner Losh "stack overflow");} 198e3e3a7aSWarner Losh 208e3e3a7aSWarner Losh 210495ed39SKyle Evans /* 220495ed39SKyle Evans ** If a call returns too many multiple returns, the callee may not have 230495ed39SKyle Evans ** stack space to accommodate all results. In this case, this macro 24*a9490b81SWarner Losh ** increases its stack space ('L->ci->top.p'). 250495ed39SKyle Evans */ 260495ed39SKyle Evans #define adjustresults(L,nres) \ 27*a9490b81SWarner Losh { if ((nres) <= LUA_MULTRET && L->ci->top.p < L->top.p) \ 28*a9490b81SWarner Losh L->ci->top.p = L->top.p; } 290495ed39SKyle Evans 300495ed39SKyle Evans 310495ed39SKyle Evans /* Ensure the stack has at least 'n' elements */ 32*a9490b81SWarner Losh #define api_checknelems(L,n) \ 33*a9490b81SWarner Losh api_check(L, (n) < (L->top.p - L->ci->func.p), \ 348e3e3a7aSWarner Losh "not enough elements in the stack") 358e3e3a7aSWarner Losh 368e3e3a7aSWarner Losh 370495ed39SKyle Evans /* 380495ed39SKyle Evans ** To reduce the overhead of returning from C functions, the presence of 390495ed39SKyle Evans ** to-be-closed variables in these functions is coded in the CallInfo's 400495ed39SKyle Evans ** field 'nresults', in a way that functions with no to-be-closed variables 410495ed39SKyle Evans ** with zero, one, or "all" wanted results have no overhead. Functions 420495ed39SKyle Evans ** with other number of wanted results, as well as functions with 430495ed39SKyle Evans ** variables to be closed, have an extra check. 440495ed39SKyle Evans */ 450495ed39SKyle Evans 460495ed39SKyle Evans #define hastocloseCfunc(n) ((n) < LUA_MULTRET) 470495ed39SKyle Evans 488c784bb8SWarner Losh /* Map [-1, inf) (range of 'nresults') into (-inf, -2] */ 490495ed39SKyle Evans #define codeNresults(n) (-(n) - 3) 508c784bb8SWarner Losh #define decodeNresults(n) (-(n) - 3) 510495ed39SKyle Evans 528e3e3a7aSWarner Losh #endif 53