include/private/base/SkSafe32.h

/*
 * Copyright 2018 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkSafe32_DEFINED
#define SkSafe32_DEFINED

#include "include/private/base/SkAssert.h"
#include "include/private/base/SkMath.h"

#include <cstdint>

static constexpr int32_t Sk64_pin_to_s32(int64_t x) {
    return x < SK_MinS32 ? SK_MinS32 : (x > SK_MaxS32 ? SK_MaxS32 : (int32_t)x);
}

static constexpr int32_t Sk32_sat_add(int32_t a, int32_t b) {
    return Sk64_pin_to_s32((int64_t)a + (int64_t)b);
}

static constexpr int32_t Sk32_sat_sub(int32_t a, int32_t b) {
    return Sk64_pin_to_s32((int64_t)a - (int64_t)b);
}

// To avoid UBSAN complaints about 2's compliment overflows
//
static constexpr int32_t Sk32_can_overflow_add(int32_t a, int32_t b) {
    return (int32_t)((uint32_t)a + (uint32_t)b);
}
static constexpr int32_t Sk32_can_overflow_sub(int32_t a, int32_t b) {
    return (int32_t)((uint32_t)a - (uint32_t)b);
}

/**
 * This is a 'safe' abs for 32-bit integers that asserts when undefined behavior would occur.
 * SkTAbs (in SkTemplates.h) is a general purpose absolute-value function.
 */
static inline int32_t SkAbs32(int32_t value) {
    SkASSERT(value != SK_NaN32);  // The most negative int32_t can't be negated.
    if (value < 0) {
        value = -value;
    }
    return value;
}

#endif