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-rwxr-xr-xmeap/ch5/src/main.rs191
1 files changed, 191 insertions, 0 deletions
diff --git a/meap/ch5/src/main.rs b/meap/ch5/src/main.rs
new file mode 100755
index 0000000..2fcf60c
--- /dev/null
+++ b/meap/ch5/src/main.rs
@@ -0,0 +1,191 @@
+////use std::mem;
+//const BIAS: i32 = 127;
+//const RADIX: f32 = 2.0;
+//
+//fn main() {
+ //let a: u16 = 0b1100_0011_1100_0011;
+ //dbg!(a);
+ ////let b: i16 = 0b1100_0011_1100_0011;
+ ////dbg!(b);
+
+// let a: f32 = 42.42;
+// let frankentype: u32 = unsafe {
+// std::mem::transmute(a)
+// };
+//
+// //println!("{:032b}", frankentype);
+
+// let mut i: u16 = 0;
+//
+// loop {
+// print!("{}\t", i);
+// if i % 10000 == 0 {
+// print!("\n");
+// }
+// i += 1000;
+// }
+
+ //let zero: u16 = 0b0000_0000_0000_0000;
+ //let one: u16 = 0b0000_0000_0000_0001;
+ //let two: u16 = 0b0000_0000_0000_0010;
+ //let big_533: u16 = 0b1111_1111_1111_1101;
+ //let big_534: u16 = 0b1111_1111_1111_1110;
+ //let big_535: u16 = 0b1111_1111_1111_1111;
+
+ //prinlt!("{}, {}, {}, ..., {}, {}, {}\n", zero, one, two, big_533, big_534, big_535);
+ //let big_533: u16 = 0b1111_1111_1111_1101;
+// let (a, b) = (200, 200);
+// let c: u8 = a + b;
+// println!("200 + 200 = {}", c);
+
+
+// let big_endian: [u8; 4] = [
+// 0xAA,
+// 0xBB,
+// 0xCC,
+// 0xDD,
+// ];
+//
+// let little_endian: [u8; 4] = [
+// 0xDD,
+// 0xCC,
+// 0xBB,
+// 0xAA,
+// ];
+//
+// let (a, b): (i32, i32) = unsafe {
+// (mem::transmute(big_endian), mem::transmute(little_endian))
+// };
+//
+// dbg!(a);
+// dbg!(b);
+
+
+// let n: f32 = 42.42;
+//
+// let (signbit, exponent, fraction) = deconstruct_f32(n);
+// let (sign, exponent, mantissa) = decode_f32_parts(signbit, exponent, fraction);
+// let reconstituted_n = f32_from_parts(sign, exponent, mantissa);
+// dbg!(n);
+// dbg!(signbit);
+// dbg!(exponent);
+// dbg!(mantissa);
+// dbg!(reconstituted_n);
+//}
+//
+//fn deconstruct_f32(n: f32) -> (u32, u32, u32) {
+// let n_: u32 = unsafe { std::mem::transmute(n) };
+//
+// let sign = (n_ >> 31) & 1;
+// let exponent = (n_ >> 23) & 0xff;
+// let fraction = 0b00000000_01111111_11111111_11111111 & n_;
+// (sign, exponent, fraction)
+//}
+//
+//fn decode_f32_parts(sign: u32, exponent: u32, fraction: u32) -> (f32, f32, f32) {
+// let signed_1 = (-1.0_f32).powf(sign as f32);
+//
+// let exponent = (exponent as i32) - BIAS;
+// let exponent = RADIX.powf(exponent as f32);
+//
+// let mut mantissa: f32 = 1.0;
+//
+// for i in 0..23_u32 {
+// let one_at_bit_i = 1 << i;
+//
+// if (one_at_bit_i & fraction) != 0 {
+// mantissa += 2_f32.powf((i as f32) - 23.0);
+// }
+// }
+//
+// (signed_1, exponent, mantissa)
+//}
+//
+//fn f32_from_parts(sign: f32, exponent: f32, mantissa: f32) -> f32 {
+// sign * exponent * mantissa
+//}
+
+fn mock_rand(n: u8) -> f32 {
+ let base: u32 = 0b0_01111110_00000000000000000000000;
+ let large_n = (n as u32) << 15;
+ let f32_bits = base | large_n;
+ let m = f32::from_bits(f32_bits);
+ 2.0 * (m - 0.5)
+}
+
+fn main() {
+ dbg!(mock_rand(0xff));
+ dbg!(mock_rand(0x77));
+ dbg!(mock_rand(0x00));
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Q7(i8);
+
+impl From<f64> for Q7 {
+ fn from(n: f64) -> Self {
+ if n >= 1.0 {
+ Q7(127)
+ }
+ else if n <= -1.0 {
+ Q7(-128)
+ }
+ else {
+ Q7((n * 128.0) as i8)
+ }
+ }
+}
+
+impl From<Q7> for f64 {
+ fn from(n: Q7) -> f64 {
+ (n.0 as f64) * 2f64.powf(-7.0)
+ }
+}
+
+impl From<f32> for Q7 {
+ fn from(n: f32) -> Self {
+ Q7::from(n as f64)
+ }
+}
+
+impl From<Q7> for f32 {
+ fn from(n: Q7) -> f32 {
+ f64::from(n) as f32
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ #[test]
+ fn out_of_bounds() {
+ assert_eq!(Q7::from(10.), Q7::from(1.));
+ assert_eq!(Q7::from(-10.), Q7::from(-1.));
+ }
+
+ #[test]
+ fn f32_to_q7() {
+ let n1: f32 = 0.7;
+ let q1 = Q7::from(n1);
+ let n2: f32 = -0.4;
+ let q2 = Q7::from(n2);
+ let n3: f32 = 123.0;
+ let q3 = Q7::from(n3);
+
+ assert_eq!(q1, Q7(89));
+ assert_eq!(q2, Q7(-51));
+ assert_eq!(q3, Q7(127));
+ }
+
+ #[test]
+ fn q7_to_f32() {
+ let q1 = Q7::from(0.7);
+ let n1 = f32::from(q1);
+ assert_eq!(n1, 0.6953125);
+
+ let q2 = Q7::from(n1);
+ let n2 = f32::from(q2);
+ assert_eq!(n1, n2);
+ }
+}