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| author | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
|---|---|---|
| committer | Adam Carpenter <53hornet@gmail.com> | 2019-03-27 15:32:37 -0400 |
| commit | 67cdcc2e12118becb823e20a40cc2687f2b8425a (patch) | |
| tree | ed92c3234b89079e6d4cf36f5e80c5ffa79def48 /meap/meap-code/ch5/ch5-u8-to-mock-rand.rs | |
| parent | e25482fca375d318a39c3b54db396b0db6e0b263 (diff) | |
| download | learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.tar.xz learning-rust-67cdcc2e12118becb823e20a40cc2687f2b8425a.zip | |
Started Rust in Action MEAP.
Diffstat (limited to 'meap/meap-code/ch5/ch5-u8-to-mock-rand.rs')
| -rw-r--r-- | meap/meap-code/ch5/ch5-u8-to-mock-rand.rs | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/meap/meap-code/ch5/ch5-u8-to-mock-rand.rs b/meap/meap-code/ch5/ch5-u8-to-mock-rand.rs new file mode 100644 index 0000000..46ac91a --- /dev/null +++ b/meap/meap-code/ch5/ch5-u8-to-mock-rand.rs @@ -0,0 +1,17 @@ +// fn mock_rand(n: u8) -> f32 {
+// (n as f32) / 255.
+// }
+
+fn mock_rand(n: u8) -> f32 {
+ let base: u32 = 0b0_01111110_00000000000000000000000; // <1> Underscores mark the sign/mantissa/exponent boundaries
+ let large_n = (n as u32) << 15; // <2> Align the input byte `n` to 32 bits, then increase its value by shifting its bits 15 places to the left
+ let f32_bits = base | large_n; // <3> Take a bitwise OR, merging the base with the input byte
+ let m = f32::from_bits(f32_bits);// <4> Interpret `f32_bits` (which is type `u32`) as an `f32`
+ 2.0 * ( m - 0.5 ) // <5> Normalize the output range
+}
+
+fn main() {
+ println!("max of input range: {:08b} -> {}", 0xff, mock_rand(0xff));
+ println!("mid of input range: {:08b} -> {}", 0x77, mock_rand(0x77));
+ println!("min of input range: {:08b} -> {}", 0x00, mock_rand(0x00));
+}
\ No newline at end of file |