2 files changed, 15 insertions, 34 deletions
diff --git a/include/tools/UnitConversion.hxx b/include/tools/UnitConversion.hxx
index e78ef315b432..57f8e39119f0 100644
--- a/include/tools/UnitConversion.hxx
+++ b/include/tools/UnitConversion.hxx
@@ -11,17 +11,32 @@
 #pragma once
 
 #include <sal/types.h>
+#include <cassert>
+#include <limits>
 
 constexpr sal_Int64 convertTwipToMm100(sal_Int64 n)
 {
+    assert(n < std::numeric_limits<sal_Int64>::max() / 127
+           && n > std::numeric_limits<sal_Int64>::min() / 127);
     return (n >= 0) ? (n * 127 + 36) / 72 : (n * 127 - 36) / 72;
 }
 
 constexpr sal_Int64 convertMm100ToTwip(sal_Int64 n)
 {
+    assert(n < std::numeric_limits<sal_Int64>::max() / 72
+           && n > std::numeric_limits<sal_Int64>::min() / 72);
     return (n >= 0) ? (n * 72 + 63) / 127 : (n * 72 - 63) / 127;
 }
 
+constexpr sal_Int64 sanitiseMm100ToTwip(sal_Int64 n)
+{
+    if (n >= std::numeric_limits<sal_Int64>::max() / 72
+        || n <= std::numeric_limits<sal_Int64>::min() / 72)
+        return n / 127 * 72; // do without correction; can not overflow here
+    else
+        return convertMm100ToTwip(n);
+}
+
 constexpr sal_Int64 convertPointToTwip(sal_Int64 nNumber) { return nNumber * 20; }
 
 constexpr sal_Int64 convertPointToMm100(sal_Int64 nNumber)
diff --git a/include/tools/helpers.hxx b/include/tools/helpers.hxx
index 381ecb206d18..abce49b3d469 100644
--- a/include/tools/helpers.hxx
+++ b/include/tools/helpers.hxx
@@ -98,38 +98,4 @@ template <typename T> [[nodiscard]] inline T NormAngle360(T angle)
     return angle;
 }
 
-/** Convert 100th-mm to twips
-
-    A twip is 1/20 of a point, one inch is equal to 72 points, and
-    one inch is 2,540 100th-mm.
-
-    Thus:
-        twips = n * 72 / 2,540 / 20
-              = n * 72 / 127
-
-    Adding 63 (half of 127) fixes truncation issues in int arithmetic.
-
-    This formula is (n>=0) ? (n*72+63) / 127 : (n*72-63) / 127
- */
-inline sal_Int64 sanitiseMm100ToTwip(sal_Int64 n)
-{
-    if (n >= 0)
-    {
-        if (o3tl::checked_multiply<sal_Int64>(n, 72, n) || o3tl::checked_add<sal_Int64>(n, 63, n))
-            n = SAL_MAX_INT64;
-    }
-    else
-    {
-        if (o3tl::checked_multiply<sal_Int64>(n, 72, n) || o3tl::checked_sub<sal_Int64>(n, 63, n))
-            n = SAL_MIN_INT64;
-    }
-    return n / 127; // 127 is 2,540 100th-mm divided by 20pts
-}
-
-/**
-* Convert Twips <-> 100th-mm
-*/
-inline constexpr sal_Int64 TwipsToHMM(sal_Int64 nTwips) { return (nTwips * 127 + 36) / 72; }
-inline constexpr sal_Int64 HMMToTwips(sal_Int64 nHMM) { return (nHMM * 72 + 63) / 127; }
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */