Move SkBase64 to utils, allow user defined encoding.

git-svn-id: http://skia.googlecode.com/svn/trunk@3148 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 231 insertions, 0 deletions

diff --git a/src/utils/SkBase64.cpp b/src/utils/SkBase64.cpp
new file mode 100644
index 0000000000..a8d4e8727f
--- /dev/null
+++ b/src/utils/SkBase64.cpp
@@ -0,0 +1,187 @@
+
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#include "SkBase64.h"
+
+#define DecodePad -2
+#define EncodePad 64
+
+static const char default_encode[] = 
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "abcdefghijklmnopqrstuvwxyz"
+    "0123456789+/=";
+
+static const signed char decodeData[] = {
+    62, -1, -1, -1, 63,
+    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, DecodePad, -1, -1,
+    -1,  0,  1,  2,  3,  4,  5,  6, 7,  8,  9, 10, 11, 12, 13, 14,
+    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
+    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
+    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
+};
+
+SkBase64::SkBase64() : fLength((size_t) -1), fData(NULL) {
+}
+
+#if defined _WIN32 && _MSC_VER >= 1300  // disable 'two', etc. may be used without having been initialized
+#pragma warning ( push )
+#pragma warning ( disable : 4701 )
+#endif
+
+SkBase64::Error SkBase64::decode(const void* srcPtr, size_t size, bool writeDestination) {
+    unsigned char* dst = (unsigned char*) fData;
+    const unsigned char* dstStart = (const unsigned char*) fData;
+    const unsigned char* src = (const unsigned char*) srcPtr;
+    bool padTwo = false;
+    bool padThree = false;
+    const unsigned char* end = src + size;
+    while (src < end) {
+        unsigned char bytes[4];
+        int byte = 0;
+        do {
+            unsigned char srcByte = *src++;
+            if (srcByte == 0)
+                goto goHome;
+            if (srcByte <= ' ')
+                continue; // treat as white space
+            if (srcByte < '+' || srcByte > 'z')
+                return kBadCharError;
+            signed char decoded = decodeData[srcByte - '+'];
+            bytes[byte] = decoded;
+            if (decoded < 0) {
+                if (decoded == DecodePad) 
+                    goto handlePad;
+                return kBadCharError;
+            } else
+                byte++;
+            if (*src)
+                continue;
+            if (byte == 0)
+                goto goHome;
+            if (byte == 4)
+                break;
+handlePad:
+            if (byte < 2)
+                return kPadError;
+            padThree = true;
+            if (byte == 2)
+                padTwo = true;
+            break;
+        } while (byte < 4);
+        int two = 0;
+        int three = 0;
+        if (writeDestination) {
+            int one = (uint8_t) (bytes[0] << 2);
+            two = bytes[1];
+            one |= two >> 4;
+            two = (uint8_t) (two << 4);
+            three = bytes[2];
+            two |= three >> 2;
+            three = (uint8_t) (three << 6);
+            three |= bytes[3];
+            SkASSERT(one < 256 && two < 256 && three < 256);
+            *dst = (unsigned char) one;
+        }
+        dst++;
+        if (padTwo) 
+            break;
+        if (writeDestination)
+            *dst = (unsigned char) two;
+        dst++;
+        if (padThree)
+            break;
+        if (writeDestination)
+            *dst = (unsigned char) three;
+        dst++;
+    }
+goHome:
+    fLength = dst - dstStart;
+    return kNoError;
+}
+
+#if defined _WIN32 && _MSC_VER >= 1300  
+#pragma warning ( pop )
+#endif
+
+size_t SkBase64::Encode(const void* srcPtr, size_t length, void* dstPtr, const char* encodeMap) {
+    const char* encode;
+    if (NULL == encodeMap) {
+        encode = default_encode;
+    } else {
+        encode = encodeMap;
+    }
+    const unsigned char* src = (const unsigned char*) srcPtr;
+    unsigned char* dst = (unsigned char*) dstPtr;
+    if (dst) {
+        size_t remainder = length % 3;
+        const unsigned char* end = &src[length - remainder];
+        while (src < end) {
+            unsigned a = *src++;
+            unsigned b = *src++;
+            unsigned c = *src++;
+            int      d = c & 0x3F;
+            c = (c >> 6 | b << 2) & 0x3F; 
+            b = (b >> 4 | a << 4) & 0x3F;
+            a = a >> 2;
+            *dst++ = encode[a];
+            *dst++ = encode[b];
+            *dst++ = encode[c];
+            *dst++ = encode[d];
+        }
+        if (remainder > 0) {
+            int k1 = 0;
+            int k2 = EncodePad;
+            int a = (uint8_t) *src++;
+            if (remainder == 2)
+            {
+                int b = *src++;
+                k1 = b >> 4;
+                k2 = (b << 2) & 0x3F;
+            }
+            *dst++ = encode[a >> 2];
+            *dst++ = encode[(k1 | a << 4) & 0x3F];
+            *dst++ = encode[k2];
+            *dst++ = encode[EncodePad];
+        }
+    }
+    return (length + 2) / 3 * 4;
+}
+
+SkBase64::Error SkBase64::decode(const char* src, size_t len) {
+    Error err = decode(src, len, false);
+    SkASSERT(err == kNoError);
+    if (err != kNoError)
+        return err;
+    fData = new char[fLength];  // should use sk_malloc/sk_free
+    decode(src, len, true);
+    return kNoError;
+}
+
+#ifdef SK_SUPPORT_UNITTEST
+void SkBase64::UnitTest() {
+    signed char all[256];
+    for (int index = 0; index < 256; index++)
+        all[index] = (signed char) (index + 1);
+    for (int offset = 0; offset < 6; offset++) {
+        size_t length = 256 - offset;
+        size_t encodeLength = Encode(all + offset, length, NULL);
+        char* src = (char*)sk_malloc_throw(encodeLength + 1);
+        Encode(all + offset, length, src);
+        src[encodeLength] = '\0';
+        SkBase64 tryMe;
+        tryMe.decode(src, encodeLength);
+        SkASSERT(length == tryMe.fLength);
+        SkASSERT(strcmp((const char*) (all + offset), tryMe.fData) == 0);
+        sk_free(src);
+        delete[] tryMe.fData;
+    }
+}
+#endif
+
+
diff --git a/src/utils/SkBase64.h b/src/utils/SkBase64.h
new file mode 100644
index 0000000000..4f3b3234f1
--- /dev/null
+++ b/src/utils/SkBase64.h
@@ -0,0 +1,44 @@
+
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef SkBase64_DEFINED
+#define SkBase64_DEFINED
+
+#include "SkTypes.h"
+
+struct SkBase64 {
+public:
+    enum Error {
+        kNoError,
+        kPadError,
+        kBadCharError
+    };
+
+    SkBase64();
+    Error decode(const char* src, size_t length);
+    char* getData() { return fData; }
+    /**
+       Base64 encodes src into dst. encode is a pointer to at least 65 chars.
+       encode[64] will be used as the pad character. Encodings other than the
+       default encoding cannot be decoded.
+    */
+    static size_t Encode(const void* src, size_t length, void* dest, const char* encode = NULL);
+
+#ifdef SK_SUPPORT_UNITTEST
+    static void UnitTest();
+#endif
+private:
+    Error decode(const void* srcPtr, size_t length, bool writeDestination);
+
+    size_t fLength;
+    char* fData;
+    friend class SkImage;
+};
+
+#endif // SkBase64_DEFINED