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  1. extern crate base64;
  2.  
  3. fn read_float_vec_from_byte_vec(v: Vec<u8>) -> Result<Vec<f32>, &'static str> {
  4.     #[inline(always)]
  5.     fn float_from_u8_slice(s: &[u8]) -> f32 {
  6.         let array = [s[0], s[1], s[2], s[3]];
  7.         unsafe { std::mem::transmute(array) }
  8.     }
  9.  
  10.     match v.len() % 4 {
  11.         0 => Ok(v.chunks(4).map(float_from_u8_slice).collect()),
  12.         _ => Err("Number not divisible by 4"),
  13.     }
  14. }
  15.  
  16. fn float_vec_as_byte_vec(values: &Vec<f32>) -> Vec<u8> {
  17.     let dest_len = values.len() * 4;
  18.     let mut result = Vec::<u8>::with_capacity(dest_len);
  19.     result.resize(dest_len, 0);
  20.     for (i, x) in values.iter().enumerate() {
  21.         let bytes: [u8; 4] = unsafe { std::mem::transmute(*x) };
  22.         result[i*4..i*4+4].copy_from_slice(&bytes[..]);
  23.     }
  24.     result
  25. }
  26.  
  27. fn show_base64_decode_error(e: base64::DecodeError) -> String {
  28.     use std::error::Error;
  29.     format!("{:?}", e.description())
  30. }
  31.  
  32. fn base64_to_f32_16_array(base64_str: &str) -> Result<[f32; 16], String>
  33. {
  34.     base64::decode(base64_str
  35.         ).map_err(show_base64_decode_error
  36.         ).and_then(read_float_vec_from_byte_vec
  37.         ).map(
  38.         |float_vec| {
  39.             let mut result: [f32; 16] = [0.0; 16];
  40.             result.copy_from_slice(&float_vec[..]);
  41.             result
  42.         }
  43.     )
  44. }
  45.  
  46. fn f32_16_array_to_base64(vals: &[f32; 16]) -> String
  47. {
  48.     base64::encode(&float_vec_as_byte_vec(&vals.to_vec()))
  49. }
  50.  
  51. #[cfg(test)]
  52. mod tests {
  53.     static VALUES: [f32; 16] = [-0.35, -0.97, 0.05, 0.49, 1.35, 1.08, -0.71, 0.27, -0.44, 0.22, -1.34, -1.17, 0.68, 0.02, -0.52, 0.83];
  54.     static BASE64_STR: &str = "MzOzvuxReL/NzEw9SOH6Ps3MrD9xPYo/j8I1v3E9ij6uR+G+rkdhPh+Fq7+PwpW/exQuPwrXozy4HgW/4XpUPw==";
  55.     #[test]
  56.     fn base64_to_f32_16_array_test() {
  57.         assert_eq!(super::base64_to_f32_16_array(&BASE64_STR), Ok(VALUES));
  58.         assert_eq!(
  59.             super::base64_to_f32_16_array("foo"),
  60.             Err("Number of bytes not divisible by 4.".to_string()));
  61.     }
  62.     #[test]
  63.     fn f32_16_array_to_base64_test() {
  64.         assert_eq!(super::f32_16_array_to_base64(&VALUES), BASE64_STR);
  65.     }
  66. }
  67.  
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https://ideone.com/jobtX1
language:
Text (text 6.10)
created:
6 years ago
visibility:
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