Convert .tgs with go libraries (and cgo) (telegram) (#1569)

This commit adds support for go/cgo tgs conversion when building with the -tags `cgo`
The default binaries are still "pure" go and uses the old way of converting.

* Move lottie_convert.py conversion code to its own file

* Add optional libtgsconverter

* Update vendor

* Apply suggestions from code review

* Update bridge/helper/libtgsconverter.go

Co-authored-by: Wim <wim@42.be>

vendor/github.com/Benau/go_rlottie/vector_varenaalloc.cpp

@@ -0,0 +1,166 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "vector_varenaalloc.h"
+#include <algorithm>
+#include <new>
+
+static char* end_chain(char*) { return nullptr; }
+
+static uint32_t first_allocated_block(uint32_t blockSize, uint32_t firstHeapAllocation) {
+    return firstHeapAllocation > 0 ? firstHeapAllocation :
+           blockSize           > 0 ? blockSize           : 1024;
+}
+
+VArenaAlloc::VArenaAlloc(char* block, size_t size, size_t firstHeapAllocation)
+    : fDtorCursor {block}
+    , fCursor     {block}
+    , fEnd        {block + ToU32(size)}
+    , fFirstBlock {block}
+    , fFirstSize  {ToU32(size)}
+    , fFirstHeapAllocationSize  {first_allocated_block(ToU32(size), ToU32(firstHeapAllocation))}
+{
+    if (size < sizeof(Footer)) {
+        fEnd = fCursor = fDtorCursor = nullptr;
+    }
+
+    if (fCursor != nullptr) {
+        this->installFooter(end_chain, 0);
+    }
+}
+
+VArenaAlloc::~VArenaAlloc() {
+    RunDtorsOnBlock(fDtorCursor);
+}
+
+void VArenaAlloc::reset() {
+    this->~VArenaAlloc();
+    new (this) VArenaAlloc{fFirstBlock, fFirstSize, fFirstHeapAllocationSize};
+}
+
+void VArenaAlloc::installFooter(FooterAction* action, uint32_t padding) {
+    assert(padding < 64);
+    int64_t actionInt = (int64_t)(intptr_t)action;
+
+    // The top 14 bits should be either all 0s or all 1s. Check this.
+    assert((actionInt << 6) >> 6 == actionInt);
+    Footer encodedFooter = (actionInt << 6) | padding;
+    memmove(fCursor, &encodedFooter, sizeof(Footer));
+    fCursor += sizeof(Footer);
+    fDtorCursor = fCursor;
+}
+
+void VArenaAlloc::installPtrFooter(FooterAction* action, char* ptr, uint32_t padding) {
+    memmove(fCursor, &ptr, sizeof(char*));
+    fCursor += sizeof(char*);
+    this->installFooter(action, padding);
+}
+
+char* VArenaAlloc::SkipPod(char* footerEnd) {
+    char* objEnd = footerEnd - (sizeof(Footer) + sizeof(int32_t));
+    int32_t skip;
+    memmove(&skip, objEnd, sizeof(int32_t));
+    return objEnd - skip;
+}
+
+void VArenaAlloc::RunDtorsOnBlock(char* footerEnd) {
+    while (footerEnd != nullptr) {
+        Footer footer;
+        memcpy(&footer, footerEnd - sizeof(Footer), sizeof(Footer));
+
+        FooterAction* action = (FooterAction*)(footer >> 6);
+        ptrdiff_t padding = footer & 63;
+
+        footerEnd = action(footerEnd) - padding;
+    }
+}
+
+char* VArenaAlloc::NextBlock(char* footerEnd) {
+    char* objEnd = footerEnd - (sizeof(Footer) + sizeof(char*));
+    char* next;
+    memmove(&next, objEnd, sizeof(char*));
+    RunDtorsOnBlock(next);
+    delete [] objEnd;
+    return nullptr;
+}
+
+void VArenaAlloc::installUint32Footer(FooterAction* action, uint32_t value, uint32_t padding) {
+    memmove(fCursor, &value, sizeof(uint32_t));
+    fCursor += sizeof(uint32_t);
+    this->installFooter(action, padding);
+}
+
+void VArenaAlloc::ensureSpace(uint32_t size, uint32_t alignment) {
+    constexpr uint32_t headerSize = sizeof(Footer) + sizeof(ptrdiff_t);
+    // The chrome c++ library we use does not define std::max_align_t.
+    // This must be conservative to add the right amount of extra memory to handle the alignment
+    // padding.
+    constexpr uint32_t alignof_max_align_t = 8;
+    constexpr uint32_t maxSize = std::numeric_limits<uint32_t>::max();
+    constexpr uint32_t overhead = headerSize + sizeof(Footer);
+    AssertRelease(size <= maxSize - overhead);
+    uint32_t objSizeAndOverhead = size + overhead;
+    if (alignment > alignof_max_align_t) {
+        uint32_t alignmentOverhead = alignment - 1;
+        AssertRelease(objSizeAndOverhead <= maxSize - alignmentOverhead);
+        objSizeAndOverhead += alignmentOverhead;
+    }
+
+    uint32_t minAllocationSize;
+    if (fFirstHeapAllocationSize <= maxSize / fFib0) {
+        minAllocationSize = fFirstHeapAllocationSize * fFib0;
+        fFib0 += fFib1;
+        std::swap(fFib0, fFib1);
+    } else {
+        minAllocationSize = maxSize;
+    }
+    uint32_t allocationSize = std::max(objSizeAndOverhead, minAllocationSize);
+
+    // Round up to a nice size. If > 32K align to 4K boundary else up to max_align_t. The > 32K
+    // heuristic is from the JEMalloc behavior.
+    {
+        uint32_t mask = allocationSize > (1 << 15) ? (1 << 12) - 1 : 16 - 1;
+        AssertRelease(allocationSize <= maxSize - mask);
+        allocationSize = (allocationSize + mask) & ~mask;
+    }
+
+    char* newBlock = new char[allocationSize];
+
+    auto previousDtor = fDtorCursor;
+    fCursor = newBlock;
+    fDtorCursor = newBlock;
+    fEnd = fCursor + allocationSize;
+    this->installPtrFooter(NextBlock, previousDtor, 0);
+}
+
+char* VArenaAlloc::allocObjectWithFooter(uint32_t sizeIncludingFooter, uint32_t alignment) {
+    uintptr_t mask = alignment - 1;
+
+restart:
+    uint32_t skipOverhead = 0;
+    bool needsSkipFooter = fCursor != fDtorCursor;
+    if (needsSkipFooter) {
+        skipOverhead = sizeof(Footer) + sizeof(uint32_t);
+    }
+    char* objStart = (char*)((uintptr_t)(fCursor + skipOverhead + mask) & ~mask);
+    uint32_t totalSize = sizeIncludingFooter + skipOverhead;
+    //std::cout<<"non POD object size = "<<totalSize<<"\n";
+    if ((ptrdiff_t)totalSize > fEnd - objStart) {
+        this->ensureSpace(totalSize, alignment);
+        goto restart;
+    }
+
+    AssertRelease((ptrdiff_t)totalSize <= fEnd - objStart);
+
+    // Install a skip footer if needed, thus terminating a run of POD data. The calling code is
+    // responsible for installing the footer after the object.
+    if (needsSkipFooter) {
+        this->installUint32Footer(SkipPod, ToU32(fCursor - fDtorCursor), 0);
+    }
+
+    return objStart;
+}