From: Kostya Shishkov <kostya.shishkov@gmail.com>
Date: Sun, 30 Apr 2017 12:37:44 +0000 (+0200)
Subject: add codebook reader
X-Git-Url: https://git.nihav.org/?a=commitdiff_plain;h=4667915ab74fdf5bb14acbb486543090232bc74b;p=nihav.git

add codebook reader
---

diff --git a/src/io/codebook.rs b/src/io/codebook.rs
new file mode 100644
index 0000000..f31e813
--- /dev/null
+++ b/src/io/codebook.rs
@@ -0,0 +1,183 @@
+use io::bitreader::BitReader;
+
+#[derive(Debug)]
+pub enum CodebookError {
+    InvalidCodebook,
+    MemoryError,
+    InvalidCode,
+}
+
+type CodebookResult<T> = Result<T, CodebookError>;
+
+pub struct FullCodebookDesc<S> {
+    code: u32,
+    bits: u8,
+    sym:  S,
+}
+
+pub struct ShortCodebookDesc {
+    code: u32,
+    bits: u8,
+}
+
+pub trait CodebookDescReader<S> {
+    fn bits(&mut self, idx: usize) -> u8;
+    fn code(&mut self, idx: usize) -> u32;
+    fn sym (&mut self, idx: usize) -> S;
+    fn len (&mut self)             -> usize;
+}
+
+#[allow(dead_code)]
+pub struct Codebook<S> {
+    table: Vec<u32>,
+    syms:  Vec<S>,
+    lut_bits: u8,
+}
+
+pub trait CodebookReader<S> {
+    fn read_cb(&mut self, cb: &Codebook<S>) -> CodebookResult<S>;
+}
+
+impl<S: Copy> Codebook<S> {
+//todo allow add escapes
+    pub fn new(cb: &mut CodebookDescReader<S>) -> CodebookResult<Self> {
+        let mut maxbits = 0;
+        let mut nnz = 0;
+        for i in 0..cb.len() {
+            let bits = cb.bits(i);
+            if bits > 0 { nnz = nnz + 1; }
+            if bits > maxbits {
+                maxbits = bits;
+            }
+        }
+        if maxbits == 0 { return Err(CodebookError::InvalidCodebook); }
+
+        let mut table: Vec<u32> = Vec::new();
+        let mut syms:  Vec<S>   = Vec::new();
+        let tab_len = 1 << maxbits;
+        table.reserve(tab_len);
+        if table.capacity() < tab_len { return Err(CodebookError::MemoryError); }
+        table.resize(tab_len, 0xFF);
+        syms.reserve(nnz);
+        if syms.capacity() < nnz { return Err(CodebookError::MemoryError); }
+
+        let mut symidx: u32 = 0;
+        for i in 0..cb.len() {
+            let bits = cb.bits(i);
+            if bits == 0 { continue; }
+            let code = cb.code(i) << (maxbits - bits);
+            let fill_len = 1 << (maxbits - bits);
+            for j in 0..fill_len {
+                let idx = (code + j) as usize;
+                table[idx] = (symidx << 8) | (bits as u32);
+            }
+            symidx = symidx + 1;
+        }
+
+        for i in 0..cb.len() {
+            if cb.bits(i) > 0 {
+                syms.push(cb.sym(i));
+            }
+        }
+
+        Ok(Codebook { table: table, syms: syms, lut_bits: maxbits })
+    }
+}
+
+impl<'a, S: Copy> CodebookReader<S> for BitReader<'a> {
+    #[allow(unused_variables)]
+    fn read_cb(&mut self, cb: &Codebook<S>) -> CodebookResult<S> {
+        let lut_idx = self.peek(cb.lut_bits) as usize;
+        let bits = cb.table[lut_idx] & 0xFF;
+        let idx  = (cb.table[lut_idx] >> 8) as usize;
+        if bits == 0xFF || (bits as isize) > self.left() {
+            return Err(CodebookError::InvalidCode);
+        }
+        if let Err(_) = self.skip(bits) {}
+        let sym = cb.syms[idx];
+        return Ok(sym)
+    }
+}
+
+pub struct FullCodebookDescReader<S> {
+    data: Vec<FullCodebookDesc<S>>,
+}
+
+impl<S> FullCodebookDescReader<S> {
+    pub fn new(data: Vec<FullCodebookDesc<S>>) -> Self {
+        FullCodebookDescReader { data: data }
+    }
+}
+
+impl<S: Copy> CodebookDescReader<S> for FullCodebookDescReader<S> {
+    fn bits(&mut self, idx: usize) -> u8  { self.data[idx].bits }
+    fn code(&mut self, idx: usize) -> u32 { self.data[idx].code }
+    fn sym (&mut self, idx: usize) -> S   { self.data[idx].sym  }
+    fn len(&mut self) -> usize { self.data.len() }
+}
+
+pub struct ShortCodebookDescReader {
+    data: Vec<ShortCodebookDesc>,
+}
+
+impl ShortCodebookDescReader {
+    pub fn new(data: Vec<ShortCodebookDesc<>>) -> Self {
+        ShortCodebookDescReader { data: data }
+    }
+}
+
+impl CodebookDescReader<u32> for ShortCodebookDescReader {
+    fn bits(&mut self, idx: usize) -> u8  { self.data[idx].bits }
+    fn code(&mut self, idx: usize) -> u32 { self.data[idx].code }
+    fn sym (&mut self, idx: usize) -> u32 { idx as u32 }
+    fn len(&mut self) -> usize { self.data.len() }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use io::bitreader::*;
+
+    #[test]
+    fn test_cb() {
+        const BITS: [u8; 2] = [0b01011011, 0b10111100];
+        let cb_desc: Vec<FullCodebookDesc<i8>> = vec!(
+            FullCodebookDesc { code: 0b0,    bits: 1, sym:  16 },
+            FullCodebookDesc { code: 0b10,   bits: 2, sym:  -3 },
+            FullCodebookDesc { code: 0b110,  bits: 3, sym:  42 },
+            FullCodebookDesc { code: 0b1110, bits: 4, sym: -42 }
+        );
+        let buf = &BITS;
+        let mut br = BitReader::new(buf, buf.len(), BitReaderMode::BE);
+        let mut cfr = FullCodebookDescReader::new(cb_desc);
+        let cb = Codebook::new(&mut cfr).unwrap();
+        assert_eq!(br.read_cb(&cb).unwrap(),  16);
+        assert_eq!(br.read_cb(&cb).unwrap(),  -3);
+        assert_eq!(br.read_cb(&cb).unwrap(),  42);
+        assert_eq!(br.read_cb(&cb).unwrap(), -42);
+        let ret = br.read_cb(&cb);
+        if let Err(e) = ret {
+            assert_eq!(e as i32, CodebookError::InvalidCode as i32);
+        } else {
+            assert_eq!(0, 1);
+        }
+
+        let scb_desc: Vec<ShortCodebookDesc> = vec!(
+            ShortCodebookDesc { code: 0b0,    bits: 1 },
+            ShortCodebookDesc { code: 0,      bits: 0 },
+            ShortCodebookDesc { code: 0b10,   bits: 2 },
+            ShortCodebookDesc { code: 0,      bits: 0 },
+            ShortCodebookDesc { code: 0,      bits: 0 },
+            ShortCodebookDesc { code: 0b110,  bits: 3 },
+            ShortCodebookDesc { code: 0,      bits: 0 },
+            ShortCodebookDesc { code: 0b1110, bits: 4 }
+        );
+        let mut br2 = BitReader::new(buf, buf.len(), BitReaderMode::BE);
+        let mut cfr = ShortCodebookDescReader::new(scb_desc);
+        let cb = Codebook::new(&mut cfr).unwrap();
+        assert_eq!(br2.read_cb(&cb).unwrap(), 0);
+        assert_eq!(br2.read_cb(&cb).unwrap(), 2);
+        assert_eq!(br2.read_cb(&cb).unwrap(), 5);
+        assert_eq!(br2.read_cb(&cb).unwrap(), 7);
+    }
+}
diff --git a/src/io/mod.rs b/src/io/mod.rs
index cb908c9..17f9c98 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -1,2 +1,5 @@
 pub mod bitreader;
+pub mod codebook;
+
 pub mod byteio;
+