From: Greg Burri <greg.burri@gmail.com>
Date: Sat, 10 Sep 2022 10:35:00 +0000 (+0200)
Subject: Doc when splitting a f32.
X-Git-Url: http://git.euphorik.ch/index.cgi?a=commitdiff_plain;h=756131d5c01e3a578d827af60aa950cc12371722;p=rust_in_action.git

Doc when splitting a f32.
---

diff --git a/ch5-data-in-depth/src/decode_f32.rs b/ch5-data-in-depth/src/decode_f32.rs
index 74bb478..b4fe497 100644
--- a/ch5-data-in-depth/src/decode_f32.rs
+++ b/ch5-data-in-depth/src/decode_f32.rs
@@ -16,9 +16,9 @@ pub fn print_f32(n: f32) {
 fn to_parts(n: f32) -> (u32, u32, u32) {
     let bits = n.to_bits();
 
-    let sign = (bits >> 31) & 1;
-    let exponent = (bits >> 23) & 0xFF;
-    let fraction = bits & 0x7F_FF_FF;
+    let sign = (bits >> 31) & 1; // 1 bit.
+    let exponent = (bits >> 23) & 0xFF; // 8 bits.
+    let fraction = bits & 0x7F_FF_FF; // 23 bits.
 
     (sign, exponent, fraction)
 }
@@ -30,7 +30,7 @@ fn decode(sign: u32, exponent: u32, fraction: u32) -> (f32, f32, f32) {
 
     let mut mantissa: f32 = 1.0;
 
-    // Mantissa is a sum of 1 + 2^(-1) + 2^(-2) + .. + 2^(-23)
+    // Mantissa is a sum of 1 + n1 * 2^(-1) + n2 * 2^(-2) + .. + n23 * 2^(-23)
     for i in 0..23 {
         let mask = 1 << i;
         let one_at_bit_i = fraction & mask;