116 lines
3.4 KiB
Rust
116 lines
3.4 KiB
Rust
// This file is part of the NRGrip project.
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//
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// Copyright (c) 2016 Matteo Cypriani <mcy@lm7.fr>
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to
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// deal in the Software without restriction, including without limitation the
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// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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// sell copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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//! Miscellaneous functions to read fixed-size data from a file.
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use std::ffi::CString;
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use std::fs::File;
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use std::io::Read;
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use std::mem;
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use ::error::NrgError;
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/// Reads a String of `size` bytes from `fd`.
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///
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/// The string will be truncated at the first null byte encountered; therefore,
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/// its length may be less than `size` characters.
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pub fn read_sized_string(fd: &mut File, size: usize)
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-> Result<String, NrgError> {
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// Read size bytes
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let mut bytes = vec!(0u8; size);
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try!(fd.read_exact(&mut bytes));
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// Truncate the vector at the first null byte
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let mut i: usize = 0;
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for b in bytes.iter() {
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if *b == 0 { break; }
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i += 1;
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}
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bytes.truncate(i);
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let cstring = CString::new(bytes)
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.expect("This Vec wasn't supposed to contain any null byte!");
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cstring.into_string().map_err(NrgError::String)
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}
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/// Reads a 64-bit unsigned integer from `fd`.
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pub fn read_u64(fd: &mut File) -> Result<u64, NrgError> {
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let mut buf = [0u8; 8];
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try!(fd.read_exact(&mut buf));
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let i: u64;
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unsafe {
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i = mem::transmute(buf);
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}
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Ok(u64::from_be(i))
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}
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/// Reads a 32-bit unsigned integer from `fd`.
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pub fn read_u32(fd: &mut File) -> Result<u32, NrgError> {
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let mut buf = [0u8; 4];
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try!(fd.read_exact(&mut buf));
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let i: u32;
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unsafe {
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i = mem::transmute(buf);
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}
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Ok(u32::from_be(i))
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}
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/// Reads a 16-bit unsigned integer from `fd`.
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pub fn read_u16(fd: &mut File) -> Result<u16, NrgError> {
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let mut buf = [0u8; 2];
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try!(fd.read_exact(&mut buf));
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let i: u16;
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unsafe {
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i = mem::transmute(buf);
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}
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Ok(u16::from_be(i))
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}
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/// Reads an unsigned byte from `fd`.
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pub fn read_u8(fd: &mut File) -> Result<u8, NrgError> {
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let mut buf = [0u8; 1];
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try!(fd.read_exact(&mut buf));
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Ok(buf[0])
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}
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/// Reads a BCD-encoded byte from `fd`.
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///
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/// If the decoded value is more than 99, which is not a valid binary-coded
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/// decimal value, the byte read is returned as is, without decoding.
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pub fn read_u8_bcd(fd: &mut File) -> Result<u8, NrgError> {
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let byte = try!(read_u8(fd));
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let tens = (byte >> 4) * 10;
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let units = (byte << 4) >> 4;
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let value = tens + units;
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if value < 100 {
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return Ok(value);
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}
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Ok(byte)
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}
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