1 files changed, 164 insertions, 0 deletions
diff --git a/core/SkDescriptor.h b/core/SkDescriptor.h
new file mode 100644
index 00000000..79b086f6
--- /dev/null
+++ b/core/SkDescriptor.h
@@ -0,0 +1,164 @@
+
+/*
+ * 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 SkDescriptor_DEFINED
+#define SkDescriptor_DEFINED
+
+#include "SkChecksum.h"
+#include "SkTypes.h"
+
+class SkDescriptor : SkNoncopyable {
+public:
+    static size_t ComputeOverhead(int entryCount) {
+        SkASSERT(entryCount >= 0);
+        return sizeof(SkDescriptor) + entryCount * sizeof(Entry);
+    }
+
+    static SkDescriptor* Alloc(size_t length) {
+        SkASSERT(SkAlign4(length) == length);
+        SkDescriptor* desc = (SkDescriptor*)sk_malloc_throw(length);
+        return desc;
+    }
+
+    static void Free(SkDescriptor* desc) {
+        sk_free(desc);
+    }
+
+    void init() {
+        fLength = sizeof(SkDescriptor);
+        fCount  = 0;
+    }
+
+    uint32_t getLength() const { return fLength; }
+
+    void* addEntry(uint32_t tag, uint32_t length, const void* data = NULL) {
+        SkASSERT(tag);
+        SkASSERT(SkAlign4(length) == length);
+        SkASSERT(this->findEntry(tag, NULL) == NULL);
+
+        Entry*  entry = (Entry*)((char*)this + fLength);
+        entry->fTag = tag;
+        entry->fLen = length;
+        if (data) {
+            memcpy(entry + 1, data, length);
+        }
+
+        fCount += 1;
+        fLength += sizeof(Entry) + length;
+        return (entry + 1); // return its data
+    }
+
+    void computeChecksum() {
+        fChecksum = SkDescriptor::ComputeChecksum(this);
+    }
+
+#ifdef SK_DEBUG
+    void assertChecksum() const {
+        SkASSERT(SkDescriptor::ComputeChecksum(this) == fChecksum);
+    }
+#endif
+
+    const void* findEntry(uint32_t tag, uint32_t* length) const {
+        const Entry* entry = (const Entry*)(this + 1);
+        int          count = fCount;
+
+        while (--count >= 0) {
+            if (entry->fTag == tag) {
+                if (length) {
+                    *length = entry->fLen;
+                }
+                return entry + 1;
+            }
+            entry = (const Entry*)((const char*)(entry + 1) + entry->fLen);
+        }
+        return NULL;
+    }
+
+    SkDescriptor* copy() const {
+        SkDescriptor* desc = SkDescriptor::Alloc(fLength);
+        memcpy(desc, this, fLength);
+        return desc;
+    }
+
+    bool equals(const SkDescriptor& other) const {
+        // probe to see if we have a good checksum algo
+//        SkASSERT(a.fChecksum != b.fChecksum || memcmp(&a, &b, a.fLength) == 0);
+
+        // the first value we should look at is the checksum, so this loop
+        // should terminate early if they descriptors are different.
+        // NOTE: if we wrote a sentinel value at the end of each, we chould
+        //       remove the aa < stop test in the loop...
+        const uint32_t* aa = (const uint32_t*)this;
+        const uint32_t* bb = (const uint32_t*)&other;
+        const uint32_t* stop = (const uint32_t*)((const char*)aa + fLength);
+        do {
+            if (*aa++ != *bb++)
+                return false;
+        } while (aa < stop);
+        return true;
+    }
+
+    uint32_t getChecksum() const { return fChecksum; }
+
+    struct Entry {
+        uint32_t fTag;
+        uint32_t fLen;
+    };
+
+#ifdef SK_DEBUG
+    uint32_t getCount() const { return fCount; }
+#endif
+
+private:
+    uint32_t fChecksum;  // must be first
+    uint32_t fLength;    // must be second
+    uint32_t fCount;
+
+    static uint32_t ComputeChecksum(const SkDescriptor* desc) {
+        const uint32_t* ptr = (const uint32_t*)desc + 1; // skip the checksum field
+        size_t len = desc->fLength - sizeof(uint32_t);
+        return SkChecksum::Compute(ptr, len);
+    }
+
+    // private so no one can create one except our factories
+    SkDescriptor() {}
+};
+
+#include "SkScalerContext.h"
+
+class SkAutoDescriptor : SkNoncopyable {
+public:
+    SkAutoDescriptor(size_t size) {
+        if (size <= sizeof(fStorage)) {
+            fDesc = (SkDescriptor*)(void*)fStorage;
+        } else {
+            fDesc = SkDescriptor::Alloc(size);
+        }
+    }
+
+    ~SkAutoDescriptor() {
+        if (fDesc != (SkDescriptor*)(void*)fStorage) {
+            SkDescriptor::Free(fDesc);
+        }
+    }
+
+    SkDescriptor* getDesc() const { return fDesc; }
+private:
+    enum {
+        kStorageSize =  sizeof(SkDescriptor)
+                        + sizeof(SkDescriptor::Entry) + sizeof(SkScalerContext::Rec)    // for rec
+                        + sizeof(SkDescriptor::Entry) + sizeof(void*)                   // for typeface
+                        + 32   // slop for occational small extras
+    };
+    SkDescriptor*   fDesc;
+    uint32_t        fStorage[(kStorageSize + 3) >> 2];
+};
+
+
+#endif