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vim-patch:8.1.2356: rand() does not use the best algorithm

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Problem:    rand() does not use the best algorithm.
Solution:   use xoshiro128** instead of xorshift. (Kaito Udagawa,
            closes vim/vim#5279)
f8c1f9200c
This commit is contained in:
Sean Dewar
2022-01-09 23:26:03 +00:00
parent 061b06a8ae
commit c97614d98f
3 changed files with 85 additions and 72 deletions
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133
src/nvim/eval/funcs.c
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@@ -6982,76 +6982,79 @@ static void f_py3eval(typval_T *argvars, typval_T *rettv, FunPtr fptr)
/// "rand()" function
static void f_rand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
{
uint32_t w;
#define SHUFFLE_XORSHIFT128 \
const uint32_t t = x ^ (x << 11); \
x = y; \
y = z; \
z = w; \
w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
list_T *l = NULL;
if (argvars[0].v_type == VAR_UNKNOWN) {
static bool rand_seed_initialized = false;
static uint32_t xyzw[4] = { 123456789, 362436069, 521288629, 88675123 };
static list_T *globl = NULL;
// When argument is not given, return random number initialized
// statically.
if (!rand_seed_initialized) {
xyzw[0] = time(NULL);
rand_seed_initialized = true;
// When no argument is given use the global seed list.
if (globl == NULL) {
// Initialize the global seed list.
f_srand(argvars, rettv, fptr);
l = rettv->vval.v_list;
if (tv_list_len(l) != 4) {
tv_clear(rettv);
goto theend;
}
globl = l;
} else {
l = globl;
}
uint32_t x = xyzw[0];
uint32_t y = xyzw[1];
uint32_t z = xyzw[2];
w = xyzw[3];
SHUFFLE_XORSHIFT128;
xyzw[0] = x;
xyzw[1] = y;
xyzw[2] = z;
xyzw[3] = w;
} else if (argvars[0].v_type == VAR_LIST) {
list_T *const l = argvars[0].vval.v_list;
l = argvars[0].vval.v_list;
if (tv_list_len(l) != 4) {
goto theend;
}
typval_T *const tvx = TV_LIST_ITEM_TV(tv_list_find(l, 0L));
typval_T *const tvy = TV_LIST_ITEM_TV(tv_list_find(l, 1L));
typval_T *const tvz = TV_LIST_ITEM_TV(tv_list_find(l, 2L));
typval_T *const tvw = TV_LIST_ITEM_TV(tv_list_find(l, 3L));
if (tvx->v_type != VAR_NUMBER) {
goto theend;
}
if (tvy->v_type != VAR_NUMBER) {
goto theend;
}
if (tvz->v_type != VAR_NUMBER) {
goto theend;
}
if (tvw->v_type != VAR_NUMBER) {
goto theend;
}
uint32_t x = tvx->vval.v_number;
uint32_t y = tvy->vval.v_number;
uint32_t z = tvz->vval.v_number;
w = tvw->vval.v_number;
SHUFFLE_XORSHIFT128;
tvx->vval.v_number = (varnumber_T)x;
tvy->vval.v_number = (varnumber_T)y;
tvz->vval.v_number = (varnumber_T)z;
tvw->vval.v_number = (varnumber_T)w;
} else {
goto theend;
}
#undef SHUFFLE_XORSHIFT128
typval_T *const tvx = TV_LIST_ITEM_TV(tv_list_find(l, 0L));
typval_T *const tvy = TV_LIST_ITEM_TV(tv_list_find(l, 1L));
typval_T *const tvz = TV_LIST_ITEM_TV(tv_list_find(l, 2L));
typval_T *const tvw = TV_LIST_ITEM_TV(tv_list_find(l, 3L));
if (tvx->v_type != VAR_NUMBER) {
goto theend;
}
if (tvy->v_type != VAR_NUMBER) {
goto theend;
}
if (tvz->v_type != VAR_NUMBER) {
goto theend;
}
if (tvw->v_type != VAR_NUMBER) {
goto theend;
}
uint32_t x = tvx->vval.v_number;
uint32_t y = tvy->vval.v_number;
uint32_t z = tvz->vval.v_number;
uint32_t w = tvw->vval.v_number;
// SHUFFLE_XOSHIRO128STARSTAR
#define ROTL(x, k) ((x << k) | (x >> (32 - k)))
const uint32_t result = ROTL(y * 5, 7) * 9;
const uint32_t t = y << 9;
z ^= x;
w ^= y;
y ^= z;
x ^= w;
z ^= t;
w = ROTL(w, 11);
#undef ROTL
tvx->vval.v_number = (varnumber_T)x;
tvy->vval.v_number = (varnumber_T)y;
tvz->vval.v_number = (varnumber_T)z;
tvw->vval.v_number = (varnumber_T)w;
rettv->v_type = VAR_NUMBER;
rettv->vval.v_number = (varnumber_T)w;
rettv->vval.v_number = (varnumber_T)result;
return;
theend:
semsg(_(e_invarg2), tv_get_string(&argvars[0]));
rettv->v_type = VAR_NUMBER;
rettv->vval.v_number = -1;
}
/// "perleval()" function
@@ -10529,6 +10532,7 @@ static void f_stdpath(typval_T *argvars, typval_T *rettv, FunPtr fptr)
static void f_srand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
{
static int dev_urandom_state = -1; // FAIL or OK once tried
uint32_t x = 0;
tv_list_alloc_ret(rettv, 4);
if (argvars[0].v_type == VAR_UNKNOWN) {
@@ -10550,26 +10554,35 @@ static void f_srand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
dev_urandom_state = FAIL;
} else {
dev_urandom_state = OK;
tv_list_append_number(rettv->vval.v_list, (varnumber_T)buf.cont.number);
x = buf.cont.number;
}
os_close(fd);
}
}
if (dev_urandom_state != OK) {
// Reading /dev/urandom doesn't work, fall back to time().
tv_list_append_number(rettv->vval.v_list, (varnumber_T)time(NULL));
x = time(NULL);
}
} else {
bool error = false;
const uint32_t x = tv_get_number_chk(&argvars[0], &error);
x = tv_get_number_chk(&argvars[0], &error);
if (error) {
return;
}
tv_list_append_number(rettv->vval.v_list, (varnumber_T)x);
}
tv_list_append_number(rettv->vval.v_list, 362436069);
tv_list_append_number(rettv->vval.v_list, 521288629);
tv_list_append_number(rettv->vval.v_list, 88675123);
uint32_t z;
#define SPLITMIX32 ( \
z = (x += 0x9e3779b9), \
z = (z ^ (z >> 16)) * 0x85ebca6b, \
z = (z ^ (z >> 13)) * 0xc2b2ae35, \
z ^ (z >> 16))
tv_list_append_number(rettv->vval.v_list, (varnumber_T)SPLITMIX32);
tv_list_append_number(rettv->vval.v_list, (varnumber_T)SPLITMIX32);
tv_list_append_number(rettv->vval.v_list, (varnumber_T)SPLITMIX32);
tv_list_append_number(rettv->vval.v_list, (varnumber_T)SPLITMIX32);
#undef SPLITMIX32
}
/*