Dirty implementation of atrac3 encoder:

 - no JS mode
 - constant quantiser for tonal components
 - gain controll implemented but produces some artifacts with real signals.
 - etc...

1 files changed, 58 insertions, 0 deletions

diff --git a/src/util.h b/src/util.h
new file mode 100644
index 0000000..f75c48e
--- /dev/null
+++ b/src/util.h
@@ -0,0 +1,58 @@
+#pragma once
+#include <cstdint>
+#include <vector>
+#include <algorithm>
+#include <cmath>
+
+#include "config.h"
+#include <cstring>
+
+template<class T>
+inline void SwapArray(T* p, const size_t len) {
+    for (size_t i = 0, j = len - 1; i < len / 2; ++i, --j) {
+        T tmp = p[i];
+        p[i] = p[j];
+        p[j] = tmp;
+    }
+}
+
+template<size_t N>
+inline void InvertSpectrInPlase(TFloat* in) {
+    for (size_t i = 0; i < N; i+=2)
+        in[i] *= -1;
+}
+
+template<size_t N>
+inline std::vector<TFloat> InvertSpectr(const TFloat* in) {
+    std::vector<TFloat> buf(N);
+    std::memcpy(&buf[0], in, N * sizeof(TFloat));
+    InvertSpectrInPlase<N>(&buf[0]);
+    return buf;
+}
+
+inline uint16_t GetFirstSetBit(uint32_t x) {
+    static const uint16_t multiplyDeBruijnBitPosition[32] = {
+        0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
+        8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31
+    };
+    x |= x >> 1;
+    x |= x >> 2;
+    x |= x >> 4;
+    x |= x >> 8;
+    x |= x >> 16;
+    return multiplyDeBruijnBitPosition[(uint32_t)(x * 0x07C4ACDDU) >> 27];
+}
+
+template<class T>
+inline uint16_t Log2FloatToIdx(T x, uint16_t shift) {
+    T t = x * shift;
+    return GetFirstSetBit(std::trunc(t));
+}
+
+template<class T>
+inline T CalcMedian(T* in, uint32_t len) {
+    std::vector<T> tmp(in, in+len);
+    std::sort(tmp.begin(), tmp.end());
+    uint32_t pos = (len - 1) / 2;
+    return tmp[pos];
+}