Initial import of Widevine Common Encryption DRM engine

Builds libwvmdrmengine.so, which is loaded by the new
MediaDrm APIs to support playback of Widevine/CENC
protected content.

Change-Id: I6f57dd37083dfd96c402cb9dd137c7d74edc8f1c

libwvdrmengine/level3/arm/string_conversions.cpp

@@ -0,0 +1,79 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+
+#include "string_conversions.h"
+
+#include <ctype.h>
+#include <iostream>
+#include <vector>
+
+#include "log.h"
+
+namespace wvcdm {
+
+static bool CharToDigit(char ch, unsigned char* digit) {
+  if (ch >= '0' && ch <= '9') {
+    *digit = ch - '0';
+  } else {
+    ch = tolower(ch);
+    if ((ch >= 'a') && (ch <= 'f')) {
+      *digit = ch - 'a' + 10;
+    } else {
+      return false;
+    }
+  }
+  return true;
+}
+
+// converts an ascii hex string(2 bytes per digit) into a decimal byte string
+std::vector<uint8_t> a2b_hex(const std::string& byte) {
+  std::vector<uint8_t> array(0);
+  unsigned int count = byte.size();
+  if (count == 0 || (count % 2) != 0) {
+    LOGE("Invalid input size %u for string %s", count, byte.c_str());
+    return array;
+  }
+
+  for (unsigned int i = 0; i < count / 2; ++i) {
+    unsigned char msb = 0;  // most significant 4 bits
+    unsigned char lsb = 0;  // least significant 4 bits
+    if (!CharToDigit(byte[i * 2], &msb) ||
+        !CharToDigit(byte[i * 2 + 1], &lsb)) {
+      LOGE("Invalid hex value %c%c at index %d", byte[i*2], byte[i*2+1], i);
+      return array;
+    }
+    array.push_back((msb << 4) | lsb);
+  }
+  return array;
+}
+
+std::string b2a_hex(const std::vector<uint8_t>& byte) {
+  return HexEncode(&byte[0], byte.size());
+}
+
+std::string HexEncode(const uint8_t* in_buffer, unsigned int size) {
+  static const char kHexChars[] = "0123456789ABCDEF";
+
+  // Each input byte creates two output hex characters.
+  std::string out_buffer(size * 2, '\0');
+
+  for (unsigned int i = 0; i < size; ++i) {
+    char byte = in_buffer[i];
+    out_buffer[(i << 1)] = kHexChars[(byte >> 4) & 0xf];
+    out_buffer[(i << 1) + 1] = kHexChars[byte & 0xf];
+  }
+  return out_buffer;
+}
+
+std::string IntToString(int value) {
+  // log10(2) ~= 0.3 bytes needed per bit or per byte log10(2**8) ~= 2.4.
+  // So round up to allocate 3 output characters per byte, plus 1 for '-'.
+  const int kOutputBufSize = 3 * sizeof(int) + 1;
+  char buffer[kOutputBufSize];
+  memset(buffer, 0, kOutputBufSize);
+  snprintf(buffer, kOutputBufSize, "%d", value);
+
+  std::string out_string(buffer, sizeof(buffer));
+  return out_string;
+}
+
+};  // namespace wvcdm