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Update Safe{Add,Mul} to match libjxl #223

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Merged
eustas merged 1 commit into from
May 12, 2026
Merged

Update Safe{Add,Mul} to match libjxl #223

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17 changes: 14 additions & 3 deletions lib/base/common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <limits>
#include <memory>
#include <string>
#include <type_traits>
Expand All @@ -33,13 +34,23 @@ constexpr inline size_t RoundUpToBlockDim(size_t dim) {
return (dim + 7) & ~static_cast<size_t>(7);
}

static inline bool JPEGLI_MAYBE_UNUSED SafeAdd(const uint64_t a,
const uint64_t b,
uint64_t& sum) {
template <typename U,
class = typename std::enable_if<std::is_unsigned<U>::value>::type>
static inline bool SafeAdd(const U a, const U b, U& sum) {
sum = a + b;
return sum >= a; // no need to check b - either sum >= both or < both.
}

template <typename U,
class = typename std::enable_if<std::is_unsigned<U>::value>::type>
static inline bool SafeMul(const U a, const U b, U& product) {
product = 0;
if (a == 0 || b == 0) return true;
if (b > (std::numeric_limits<U>::max() / a)) return false;
product = a * b;
return true;
}

template <typename T1, typename T2>
constexpr inline T1 DivCeil(T1 a, T2 b) {
return (a + b - 1) / b;
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