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https://github.com/lua/lua
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53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
/*
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** $Id: lapi.h $
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** Auxiliary functions from Lua API
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** See Copyright Notice in lua.h
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*/
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#ifndef lapi_h
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#define lapi_h
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#include "llimits.h"
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#include "lstate.h"
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/* Increments 'L->top.p', checking for stack overflows */
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#define api_incr_top(L) {L->top.p++; \
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api_check(L, L->top.p <= L->ci->top.p, \
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"stack overflow");}
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/*
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** If a call returns too many multiple returns, the callee may not have
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** stack space to accommodate all results. In this case, this macro
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** increases its stack space ('L->ci->top.p').
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*/
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#define adjustresults(L,nres) \
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{ if ((nres) <= LUA_MULTRET && L->ci->top.p < L->top.p) \
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L->ci->top.p = L->top.p; }
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/* Ensure the stack has at least 'n' elements */
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#define api_checknelems(L,n) \
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api_check(L, (n) < (L->top.p - L->ci->func.p), \
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"not enough elements in the stack")
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/*
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** To reduce the overhead of returning from C functions, the presence of
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** to-be-closed variables in these functions is coded in the CallInfo's
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** field 'nresults', in a way that functions with no to-be-closed variables
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** with zero, one, or "all" wanted results have no overhead. Functions
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** with other number of wanted results, as well as functions with
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** variables to be closed, have an extra check.
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*/
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#define hastocloseCfunc(n) ((n) < LUA_MULTRET)
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/* Map [-1, inf) (range of 'nresults') into (-inf, -2] */
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#define codeNresults(n) (-(n) - 3)
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#define decodeNresults(n) (-(n) - 3)
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#endif
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