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in 'table.sort': 'typedef' for type of indices + removed stack check

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(recursion is in the C stack, not in the Lua stack!)
This commit is contained in:
Roberto Ierusalimschy 2015-12-14 09:57:38 -02:00
parent 656b3cea1b
commit e383941652
1 changed files with 17 additions and 16 deletions
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33
ltablib.c
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@ -1,5 +1,5 @@
/*
** $Id: ltablib.c,v 1.89 2015/11/24 16:54:32 roberto Exp roberto $
** $Id: ltablib.c,v 1.90 2015/11/25 12:48:57 roberto Exp roberto $
** Library for Table Manipulation
** See Copyright Notice in lua.h
*/
@ -232,6 +232,10 @@ static int unpack (lua_State *L) {
*/
/* type for array indices */
typedef unsigned int IdxT;
/*
** Produce a "random" 'unsigned int' to randomize pivot choice. This
** macro is used only when 'sort' detects a big imbalance in the result
@ -270,7 +274,7 @@ static unsigned int l_randomizePivot (void) {
#define RANLIMIT 100u
static void set2 (lua_State *L, unsigned int i, unsigned int j) {
static void set2 (lua_State *L, IdxT i, IdxT j) {
lua_seti(L, 1, i);
lua_seti(L, 1, j);
}
@ -303,10 +307,9 @@ static int sort_comp (lua_State *L, int a, int b) {
** Pos-condition: a[lo .. i - 1] <= a[i] == P <= a[i + 1 .. up]
** returns 'i'.
*/
static unsigned int partition (lua_State *L, unsigned int lo,
unsigned int up) {
unsigned int i = lo; /* will be incremented before first use */
unsigned int j = up - 1; /* will be decremented before first use */
static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
IdxT i = lo; /* will be incremented before first use */
IdxT j = up - 1; /* will be decremented before first use */
/* loop invariant: a[lo .. i] <= P <= a[j .. up] */
for (;;) {
/* next loop: repeat ++i while a[i] < P */
@ -340,10 +343,9 @@ static unsigned int partition (lua_State *L, unsigned int lo,
** Choose an element in the middle (2nd-3th quarters) of [lo,up]
** "randomized" by 'rnd'
*/
static unsigned int choosePivot (unsigned int lo, unsigned int up,
unsigned int rnd) {
unsigned int r4 = (unsigned int)(up - lo) / 4u; /* range/4 */
unsigned int p = rnd % (r4 * 2) + (lo + r4);
static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
IdxT r4 = (up - lo) / 4; /* range/4 */
IdxT p = rnd % (r4 * 2) + (lo + r4);
lua_assert(lo + r4 <= p && p <= up - r4);
return p;
}
@ -352,11 +354,11 @@ static unsigned int choosePivot (unsigned int lo, unsigned int up,
/*
** QuickSort algorithm (recursive function)
*/
static void auxsort (lua_State *L, unsigned int lo, unsigned int up,
static void auxsort (lua_State *L, IdxT lo, IdxT up,
unsigned int rnd) {
while (lo < up) { /* loop for tail recursion */
unsigned int p; /* Pivot index */
unsigned int n; /* to be used later */
IdxT p; /* Pivot index */
IdxT n; /* to be used later */
/* sort elements 'lo', 'p', and 'up' */
lua_geti(L, 1, lo);
lua_geti(L, 1, up);
@ -400,7 +402,7 @@ static void auxsort (lua_State *L, unsigned int lo, unsigned int up,
n = up - p; /* size of smaller interval */
up = p - 1; /* tail call for [lo .. p - 1] (lower interval) */
}
if ((up - lo) / 128u > n) /* partition too imbalanced? */
if ((up - lo) / 128 > n) /* partition too imbalanced? */
rnd = l_randomizePivot(); /* try a new randomization */
} /* tail call auxsort(L, lo, up, rnd) */
}
@ -410,11 +412,10 @@ static int sort (lua_State *L) {
lua_Integer n = aux_getn(L, 1, TAB_RW);
if (n > 1) { /* non-trivial interval? */
luaL_argcheck(L, n < INT_MAX, 1, "array too big");
luaL_checkstack(L, 40, ""); /* assume array is smaller than 2^40 */
if (!lua_isnoneornil(L, 2)) /* is there a 2nd argument? */
luaL_checktype(L, 2, LUA_TFUNCTION); /* must be a function */
lua_settop(L, 2); /* make sure there are two arguments */
auxsort(L, 1, (unsigned int)n, 0u);
auxsort(L, 1, (IdxT)n, 0);
}
return 0;
}