From f147abda5f37479cdaa0662cda4f5f7fa4236355 Mon Sep 17 00:00:00 2001
From: Hexa Dust <hxd@hexadust.net>
Date: Fri, 18 Jul 2025 21:19:30 +0100
Subject: [PATCH] fix for float parsing of exactly 10.0

---
 src/calc.rs | 11 ++++++++++-
 src/lib.rs  | 26 +++++++++++++++++++++++---
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/calc.rs b/src/calc.rs
index 78b41c5..803f79f 100644
--- a/src/calc.rs
+++ b/src/calc.rs
@@ -19,7 +19,7 @@ impl Display for StackCalcError {
         match self {
             StackCalcError::StackOverflow => f.write_str("stack overflow"),
             StackCalcError::StackUnderflow => f.write_str("stack underflow"),
-            StackCalcError::DecimalError(de) => de.fmt(f),
+            StackCalcError::DecimalError(de) => Display::fmt(de, f),
         }
     }
 }
@@ -185,4 +185,13 @@ mod tests {
         ));
         Ok(())
     }
+
+    #[test]
+    fn test_add_10() -> Result<(), StackCalcError> {
+        let mut calc = StackCalc::<f64, 3, 5>::default();
+        calc.push(Decimal::new(false, [3, 0, 0, 0, 0], false, 0))?;
+        calc.push(Decimal::new(false, [7, 0, 0, 0, 0], false, 0))?;
+        assert_eq!(calc.add()?, Decimal::new(false, [1, 0, 0, 0, 0], false, 1));
+        Ok(())
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index b5acf1a..bd5e69f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -81,7 +81,7 @@ impl<const SIZE: usize, EXP: PrimInt + Unsigned> Decimal<SIZE, EXP> {
         }
         let mut exponent: EXP = zero();
         let minus_exponent = f < one() && f > zero();
-        while f > F::from(10).unwrap() {
+        while f >= F::from(10).unwrap() {
             f = f / F::from(10).unwrap();
             exponent = exponent
                 .checked_add(&one())
@@ -234,6 +234,11 @@ mod tests {
     use super::*;
     use arrayvec::ArrayString;
 
+    fn round_f(f: f64, d: i32) -> f64 {
+        let m = 10.0.powi(d);
+        (f * m).round() / m
+    }
+
     #[test]
     fn float_to_decimal_zero() {
         let dec = Decimal::<5>::try_from(0.0).unwrap();
@@ -243,6 +248,15 @@ mod tests {
         assert_eq!(dec.exponent, 0)
     }
 
+    #[test]
+    fn float_to_decimal_ten() {
+        let dec = Decimal::<5>::try_from(10.0).unwrap();
+        assert!(!dec.minus);
+        assert_eq!(dec.significant, [1, 0, 0, 0, 0]);
+        assert!(!dec.minus_exponent);
+        assert_eq!(dec.exponent, 1)
+    }
+
     #[test]
     fn float_to_decimal_pos_big() {
         let dec = Decimal::<7>::try_from(1337.42).unwrap();
@@ -344,7 +358,10 @@ mod tests {
         dec.significant = [1, 3, 3, 7, 4, 2, 1];
         dec.minus_exponent = true;
         dec.exponent = 2;
-        assert_eq!(f64::try_from(dec).unwrap(), 0.01337421);
+        assert_eq!(
+            round_f(f64::try_from(dec).unwrap(), 8),
+            round_f(0.01337421, 8)
+        );
     }
 
     #[test]
@@ -363,7 +380,10 @@ mod tests {
         dec.significant = [1, 3, 3, 7, 4, 2, 1];
         dec.minus_exponent = true;
         dec.exponent = 2;
-        assert_eq!(f64::try_from(dec).unwrap(), -0.01337421);
+        assert_eq!(
+            round_f(f64::try_from(dec).unwrap(), 8),
+            round_f(-0.01337421, 8)
+        );
     }
 
     #[test]