From 7e8ee5ed9cad6484e9f13f81731b102ced58402e Mon Sep 17 00:00:00 2001 From: Adam Carpenter Date: Tue, 9 Jul 2019 15:14:04 -0400 Subject: Init. --- meap/meap-code/ch5/ch5-u8-to-mock-rand.rs | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) create mode 100755 meap/meap-code/ch5/ch5-u8-to-mock-rand.rs (limited to 'meap/meap-code/ch5/ch5-u8-to-mock-rand.rs') 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 100755 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 -- cgit v1.2.3