From 7b3624cc1d514c604ad38a9798169c069c84f2c4 Mon Sep 17 00:00:00 2001
From: David Himmelstrup <lemmih@gmail.com>
Date: Wed, 14 Sep 2022 16:15:13 +0200
Subject: [PATCH] Improve performance when writing a single digit.

---
 integer/src/fmt/digit_writer.rs | 9 +++++++++
 integer/src/fmt/power_two.rs    | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/integer/src/fmt/digit_writer.rs b/integer/src/fmt/digit_writer.rs
index 94ef495..d3a403c 100644
--- a/integer/src/fmt/digit_writer.rs
+++ b/integer/src/fmt/digit_writer.rs
@@ -41,6 +41,15 @@ impl<'a> DigitWriter<'a> {
         Ok(())
     }
 
+    pub fn write_digit(&mut self, digit: u8) -> fmt::Result {
+        self.buffer[self.buffer_len] = digit;
+        self.buffer_len += 1;
+        if self.buffer_len == BUFFER_LEN {
+            self.flush()?;
+        }
+        Ok(())
+    }
+
     /// Must call flush to make sure all the data is written.
     pub fn flush(&mut self) -> fmt::Result {
         let buffer_len_rounded = math::round_up(self.buffer_len, arch::digits::DIGIT_CHUNK_LEN);
diff --git a/integer/src/fmt/power_two.rs b/integer/src/fmt/power_two.rs
index cd40f78..e89172f 100644
--- a/integer/src/fmt/power_two.rs
+++ b/integer/src/fmt/power_two.rs
@@ -168,7 +168,8 @@ impl PreparedForFormatting for PreparedLarge<'_> {
                 bits -= self.log_radix;
                 digit = ((word >> bits) & mask) as u8;
             }
-            digit_writer.write(&[digit])?;
+            // digit_writer.write(&[digit])?;
+            digit_writer.write_digit(digit)?;
         }
         debug_assert_eq!(bits, 0);
         Ok(())