From ce36d80eb346b48895121fed61adff5a20cd7c46 Mon Sep 17 00:00:00 2001
From: Rosen Penev <rosenp@gmail.com>
Date: Mon, 3 Mar 2025 18:42:58 -0800
Subject: [PATCH] replace pow with exp2

A boneheaded mistake when converting std::exp and std::log(2). exp2 is
simpler.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 src/canonmn_int.cpp |  4 ++--
 src/nikonmn_int.cpp | 10 +++++-----
 src/tags_int.cpp    |  4 ++--
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/canonmn_int.cpp b/src/canonmn_int.cpp
index d40145ba21..a95562feb0 100644
--- a/src/canonmn_int.cpp
+++ b/src/canonmn_int.cpp
@@ -3028,7 +3028,7 @@ std::ostream& CanonMakerNote::printLe0x0000(std::ostream& os, const Value& value
 
 std::ostream& CanonMakerNote::printSi0x0001(std::ostream& os, const Value& value, const ExifData*) {
   if (value.typeId() == unsignedShort && value.count() > 0) {
-    os << std::pow(2.0F, canonEv(value.toInt64()) / 32) * 100.0F;
+    os << std::exp2(canonEv(value.toInt64()) / 32) * 100.0F;
   }
   return os;
 }
@@ -3036,7 +3036,7 @@ std::ostream& CanonMakerNote::printSi0x0001(std::ostream& os, const Value& value
 std::ostream& CanonMakerNote::printSi0x0002(std::ostream& os, const Value& value, const ExifData*) {
   if (value.typeId() == unsignedShort && value.count() > 0) {
     // Ported from Exiftool by Will Stokes
-    os << std::pow(2.0F, canonEv(value.toInt64())) * 100.0F / 32.0F;
+    os << std::exp2(canonEv(value.toInt64())) * (100.0F / 32.0F);
   }
   return os;
 }
diff --git a/src/nikonmn_int.cpp b/src/nikonmn_int.cpp
index 17e7137ba1..19baf27b85 100644
--- a/src/nikonmn_int.cpp
+++ b/src/nikonmn_int.cpp
@@ -1045,7 +1045,7 @@ static void printFlashCompensationValue(std::ostream& os, const unsigned char va
     }
     const auto mod = value % 6;
     auto temp = (value < 6) ? 0 : (value - mod) / 6;
-    os << "1/" << std::pow(2, temp);
+    os << "1/" << std::exp2(temp);
     if (mod != 0) {
       os << " (-";
       switch (mod) {
@@ -1740,7 +1740,7 @@ const TagInfo* Nikon3MakerNote::tagListLd4() {
 }
 
 std::ostream& Nikon3MakerNote::printIiIso(std::ostream& os, const Value& value, const ExifData*) {
-  auto v = std::lround(100.0 * std::pow(2.0, (value.toInt64() / 12.0) - 5));
+  auto v = std::lround(100.0 * std::exp2((value.toInt64() / 12.0) - 5));
   return os << v;
 }
 
@@ -3304,7 +3304,7 @@ std::ostream& Nikon3MakerNote::printAperture(std::ostream& os, const Value& valu
   if (val == 0)
     return os << _("n/a");
 
-  return os << stringFormat("F{:.1f}", std::pow(2.0, val / 24.0));
+  return os << stringFormat("F{:.1f}", std::exp2(val / 24.0));
 }
 
 std::ostream& Nikon3MakerNote::printFocal(std::ostream& os, const Value& value, const ExifData*) {
@@ -3315,7 +3315,7 @@ std::ostream& Nikon3MakerNote::printFocal(std::ostream& os, const Value& value,
   if (val == 0)
     return os << _("n/a");
 
-  return os << stringFormat("{:.1f} mm", 5.0 * std::pow(2.0, val / 24.0));
+  return os << stringFormat("{:.1f} mm", 5.0 * std::exp2(val / 24.0));
 }
 
 std::ostream& Nikon3MakerNote::printFStops(std::ostream& os, const Value& value, const ExifData*) {
@@ -3919,7 +3919,7 @@ std::ostream& Nikon3MakerNote::printApertureLd4(std::ostream& os, const Value& v
   if (temp == 0)
     return os << _("n/a");
 
-  return os << stringFormat("F{:.1f}", std::pow(2.0, (temp / 384.0) - 1.0));
+  return os << stringFormat("F{:.1f}", std::exp2((temp / 384.0) - 1.0));
 }
 std::ostream& Nikon3MakerNote::printFocalLd4(std::ostream& os, const Value& value, const ExifData*) {
   if (value.count() != 1 || value.typeId() != unsignedShort) {
diff --git a/src/tags_int.cpp b/src/tags_int.cpp
index a9ef750b1a..e82a0a44d5 100644
--- a/src/tags_int.cpp
+++ b/src/tags_int.cpp
@@ -2592,7 +2592,7 @@ std::ostream& printBitmask(std::ostream& os, const Value& value, const ExifData*
 }
 
 float fnumber(float apertureValue) {
-  float result = std::pow(2.0F, apertureValue / 2.F);
+  float result = std::exp2(apertureValue / 2.F);
   if (std::abs(result - 3.5) < 0.1) {
     result = 3.5;
   }
@@ -2601,7 +2601,7 @@ float fnumber(float apertureValue) {
 
 URational exposureTime(float shutterSpeedValue) {
   URational ur(1, 1);
-  const double tmp = std::pow(2.0, shutterSpeedValue);
+  const double tmp = std::exp2(shutterSpeedValue);
   if (tmp > 1) {
     const double x = std::round(tmp);
     // Check that x is within the range of a uint32_t before casting.