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// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/bigint/vector-arithmetic.h"
#include "src/bigint/bigint-internal.h"
#include "src/bigint/digit-arithmetic.h"
namespace v8 {
namespace bigint {
digit_t AddAndReturnOverflow(RWDigits Z, Digits X) {
X.Normalize();
if (X.len() == 0) return 0;
digit_t carry = 0;
int i = 0;
for (; i < X.len(); i++) {
Z[i] = digit_add3(Z[i], X[i], carry, &carry);
}
for (; i < Z.len() && carry != 0; i++) {
Z[i] = digit_add2(Z[i], carry, &carry);
}
return carry;
}
digit_t SubAndReturnBorrow(RWDigits Z, Digits X) {
X.Normalize();
if (X.len() == 0) return 0;
digit_t borrow = 0;
int i = 0;
for (; i < X.len(); i++) {
Z[i] = digit_sub2(Z[i], X[i], borrow, &borrow);
}
for (; i < Z.len() && borrow != 0; i++) {
Z[i] = digit_sub(Z[i], borrow, &borrow);
}
return borrow;
}
void Add(RWDigits Z, Digits X, Digits Y) {
if (X.len() < Y.len()) {
return Add(Z, Y, X);
}
int i = 0;
digit_t carry = 0;
for (; i < Y.len(); i++) {
Z[i] = digit_add3(X[i], Y[i], carry, &carry);
}
for (; i < X.len(); i++) {
Z[i] = digit_add2(X[i], carry, &carry);
}
for (; i < Z.len(); i++) {
Z[i] = carry;
carry = 0;
}
}
void Subtract(RWDigits Z, Digits X, Digits Y) {
X.Normalize();
Y.Normalize();
DCHECK(X.len() >= Y.len());
int i = 0;
digit_t borrow = 0;
for (; i < Y.len(); i++) {
Z[i] = digit_sub2(X[i], Y[i], borrow, &borrow);
}
for (; i < X.len(); i++) {
Z[i] = digit_sub(X[i], borrow, &borrow);
}
DCHECK(borrow == 0); // NOLINT(readability/check)
for (; i < Z.len(); i++) Z[i] = 0;
}
digit_t AddAndReturnCarry(RWDigits Z, Digits X, Digits Y) {
DCHECK(Z.len() >= Y.len() && X.len() >= Y.len());
digit_t carry = 0;
for (int i = 0; i < Y.len(); i++) {
Z[i] = digit_add3(X[i], Y[i], carry, &carry);
}
return carry;
}
digit_t SubtractAndReturnBorrow(RWDigits Z, Digits X, Digits Y) {
DCHECK(Z.len() >= Y.len() && X.len() >= Y.len());
digit_t borrow = 0;
for (int i = 0; i < Y.len(); i++) {
Z[i] = digit_sub2(X[i], Y[i], borrow, &borrow);
}
return borrow;
}
bool AddSigned(RWDigits Z, Digits X, bool x_negative, Digits Y,
bool y_negative) {
if (x_negative == y_negative) {
Add(Z, X, Y);
return x_negative;
}
if (GreaterThanOrEqual(X, Y)) {
Subtract(Z, X, Y);
return x_negative;
}
Subtract(Z, Y, X);
return !x_negative;
}
bool SubtractSigned(RWDigits Z, Digits X, bool x_negative, Digits Y,
bool y_negative) {
if (x_negative != y_negative) {
Add(Z, X, Y);
return x_negative;
}
if (GreaterThanOrEqual(X, Y)) {
Subtract(Z, X, Y);
return x_negative;
}
Subtract(Z, Y, X);
return !x_negative;
}
void AddOne(RWDigits Z, Digits X) {
digit_t carry = 1;
int i = 0;
for (; carry > 0 && i < X.len(); i++) Z[i] = digit_add2(X[i], carry, &carry);
if (carry > 0) Z[i++] = carry;
for (; i < X.len(); i++) Z[i] = X[i];
for (; i < Z.len(); i++) Z[i] = 0;
}
void SubtractOne(RWDigits Z, Digits X) {
digit_t borrow = 1;
int i = 0;
for (; borrow > 0; i++) Z[i] = digit_sub(X[i], borrow, &borrow);
for (; i < X.len(); i++) Z[i] = X[i];
for (; i < Z.len(); i++) Z[i] = 0;
}
} // namespace bigint
} // namespace v8
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