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Download(c) 2005-2025 XLOG Technologies AG
/**
* Modern Albufeira Prolog Interpreter
*
* Warranty & Liability
* To the extent permitted by applicable law and unless explicitly
* otherwise agreed upon, XLOG Technologies AG makes no warranties
* regarding the provided information. XLOG Technologies AG assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies AG.
*
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies AG. If the company was not the originator of some
* excerpts, XLOG Technologies AG has at least obtained the right to
* reproduce, change and translate the information.
*
* Reproduction is restricted to the whole unaltered document. Reproduction
* of the information is only allowed for non-commercial uses. Selling,
* giving away or letting of the execution of the library is prohibited.
* The library can be distributed as part of your applications and libraries
* for execution provided this comment remains unchanged.
*
* Restrictions
* Only to be distributed with programs that add significant and primary
* functionality to the library. Not to be distributed with additional
* software intended to replace any components of the library.
*
* Trademarks
* Jekejeke is a registered trademark of XLOG Technologies AG.
*/
import {check_integer, is_bigint, exec_eval, deref, exec_build,
widen_bigint, norm_bigint, make_error, Compound,
add, make_check, norm_float, exec_unify, make_arithmetic
} from "../../nova/core.mjs";
/*********************************************************************/
/* Random Numbers */
/*********************************************************************/
/**
* random(F):
* The predicate succeeds in F with a uniform random 64-bit
* floating point value in the interval [0..1).
*/
function test_random(args) {
let alpha = norm_float(Math.random());
return exec_unify(args[0], alpha);
}
/*********************************************************************/
/* msb/2, lsb/2 and testbit/2 */
/*********************************************************************/
/**
* msb(X):
* If X is an integer, then the function returns the most significant bit.
*/
function arit_msb(args) {
let alpha = exec_eval(args[0]);
check_integer(alpha);
return bigint_msb(alpha < 0 ? ~alpha : alpha);
}
/**
* lsb(X):
* If X is an integer, then the function returns the least significant bit.
*/
function arit_lsb(args) {
let alpha = exec_eval(args[0]);
check_integer(alpha);
return bigint_msb(alpha & -alpha);
}
function bigint_msb(alpha) {
if (!is_bigint(alpha)) {
return 31 - Math.clz32(alpha);
} else {
alpha = alpha.toString(16);
return 31 - Math.clz32(parseInt(alpha.at(0), 16)) + (alpha.length - 1) * 4;
}
}
/**
* popcount(X):
* If X is an integer, then the function returns the number of ones.
*/
function arit_popcount(args) {
let alpha = exec_eval(args[0]);
check_integer(alpha);
if (alpha < 0) {
alpha = -alpha;
return bigint_popcount(alpha) + bigint_msb(alpha & -alpha) - 1;
} else {
return bigint_popcount(alpha);
}
}
function bigint_popcount(alpha) {
if (!is_bigint(alpha)) {
return smallint_popcount(alpha);
} else {
alpha = alpha.toString(16);
let res = 0;
let i = alpha.length % 8;
if (i > 0)
res += smallint_popcount(parseInt(alpha.substring(0,i), 16));
for (; i < alpha.length; i+=8)
res += smallint_popcount(parseInt(alpha.substring(i,i+8), 16));
return res;
}
}
function smallint_popcount(i) {
i = i - ((i >>> 1) & 0x55555555);
i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
i = (i + (i >>> 4)) & 0x0f0f0f0f;
i = i + (i >>> 8);
i = i + (i >>> 16);
return i & 0x3f;
}
/**
* testbit(X, Y):
* The predicate succeeds when X /\ (1 << Y) =\= 0.
*/
function test_testbit(args) {
let alpha = deref(exec_build(args[0]));
check_integer(alpha);
let beta = deref(exec_build(args[1]));
check_integer(beta);
if (beta < 0)
throw make_error(new Compound("domain_error",
["not_less_than_zero", beta]));
return number_testbit(alpha, beta);
}
function number_testbit(alpha, beta) {
if (!is_bigint(alpha) && !is_bigint(beta)) {
if (beta < 31) {
return (alpha & (1 << beta)) !== 0;
} else {
return alpha < 0;
}
} else {
return (widen_bigint(alpha) & (1n << widen_bigint(beta))) !== 0n;
}
}
/*********************************************************************/
/* divmod/4 */
/*********************************************************************/
/**
* divmod(X, Y, Z, T):
* If X and Y are both integers then the predicate succeeds in
* Z with the division of X by Y, and in T with the modulo of X by Y.
*/
function test_divmod(args) {
let alpha = deref(exec_build(args[0]));
check_integer(alpha);
let beta = deref(exec_build(args[1]));
check_integer(beta);
let divres;
let modres;
if (!is_bigint(alpha) && !is_bigint(beta)) {
divres = Math.floor(alpha / beta);
modres = alpha - divres*beta;
} else {
alpha = widen_bigint(alpha);
beta = widen_bigint(beta);
divres = bigint_div(alpha, beta);
modres = alpha - divres*beta;
divres = norm_bigint(divres);
modres = norm_bigint(modres);
}
if (!exec_unify(args[2], divres))
return false;
return exec_unify(args[3], modres);
}
function bigint_div(alpha, beta) {
let temp = alpha / beta;
if ((alpha < 0n) !== (beta < 0n)) {
let res = alpha % beta;
if (res !== 0n)
temp--;
}
return temp;
}
/*********************************************************************/
/* Bit Lib Init */
/*********************************************************************/
export function main() {
add("random", 1, make_check(test_random));
add("msb", 2, make_arithmetic(arit_msb));
add("lsb", 2, make_arithmetic(arit_lsb));
add("popcount", 2, make_arithmetic(arit_popcount));
add("testbit", 2, make_check(test_testbit));
add("divmod", 4, make_check(test_divmod));
}