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Comments and order of hashing macros in 'ltable.c'.
This commit is contained in:
Roberto Ierusalimschy 2021-03-12 11:29:34 -03:00
parent 05b13651f9
commit 014daf43cb
1 changed files with 40 additions and 21 deletions
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61
ltable.c
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@ -68,20 +68,25 @@
#define MAXHSIZE luaM_limitN(1u << MAXHBITS, Node)
/*
** When the original hash value is good, hashing by a power of 2
** avoids the cost of '%'.
*/
#define hashpow2(t,n) (gnode(t, lmod((n), sizenode(t))))
/*
** for other types, it is better to avoid modulo by power of 2, as
** they can have many 2 factors.
*/
#define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))
#define hashstr(t,str) hashpow2(t, (str)->hash)
#define hashboolean(t,p) hashpow2(t, p)
#define hashint(t,i) hashpow2(t, i)
/*
** for some types, it is better to avoid modulus by power of 2, as
** they tend to have many 2 factors.
*/
#define hashmod(t,n) (gnode(t, ((n) % ((sizenode(t)-1)|1))))
#define hashpointer(t,p) hashmod(t, point2uint(p))
@ -135,24 +140,38 @@ static int l_hashfloat (lua_Number n) {
*/
static Node *mainposition (const Table *t, int ktt, const Value *kvl) {
switch (withvariant(ktt)) {
case LUA_VNUMINT:
return hashint(t, ivalueraw(*kvl));
case LUA_VNUMFLT:
return hashmod(t, l_hashfloat(fltvalueraw(*kvl)));
case LUA_VSHRSTR:
return hashstr(t, tsvalueraw(*kvl));
case LUA_VLNGSTR:
return hashpow2(t, luaS_hashlongstr(tsvalueraw(*kvl)));
case LUA_VNUMINT: {
lua_Integer key = ivalueraw(*kvl);
return hashint(t, key);
}
case LUA_VNUMFLT: {
lua_Number n = fltvalueraw(*kvl);
return hashmod(t, l_hashfloat(n));
}
case LUA_VSHRSTR: {
TString *ts = tsvalueraw(*kvl);
return hashstr(t, ts);
}
case LUA_VLNGSTR: {
TString *ts = tsvalueraw(*kvl);
return hashpow2(t, luaS_hashlongstr(ts));
}
case LUA_VFALSE:
return hashboolean(t, 0);
case LUA_VTRUE:
return hashboolean(t, 1);
case LUA_VLIGHTUSERDATA:
return hashpointer(t, pvalueraw(*kvl));
case LUA_VLCF:
return hashpointer(t, fvalueraw(*kvl));
default:
return hashpointer(t, gcvalueraw(*kvl));
case LUA_VLIGHTUSERDATA: {
void *p = pvalueraw(*kvl);
return hashpointer(t, p);
}
case LUA_VLCF: {
lua_CFunction f = fvalueraw(*kvl);
return hashpointer(t, f);
}
default: {
GCObject *o = gcvalueraw(*kvl);
return hashpointer(t, o);
}
}
}