Author :
Stephen Kyle
Date :
2018-09-27 12:15:46
Hash :9402ac5c Message :decode: faster huffman code loading on 32-bit Arm (#703)
* platform: add macro for using the 'aligned' attribute
* decode: add accessor macros for HuffmanCode fields
Adds a constructor function for building HuffmanCode values
so they can be accessed quickly on different architectures.
Also adds macros for marking a HuffmanCode table pointer
that can be accessed quickly (BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD),
adjusting the index into that table (BROTLI_HC_ADJUST_TABLE_INDEX),
and getting the .bits or .value fields out of the table at the
current index (BROTLI_HC_GET_BITS/VALUE).
For example, assuming |table| contains a HuffmanCode pointer:
BROTLI_HC_MARK_TABLE_FOR_FAST_LOAD(table);
BROTLI_HC_ADJUST_TABLE_INDEX(table, index_into_table);
*bits = BROTLI_HC_GET_BITS(table);
*value = BROTLI_HC_GET_VALUE(table);
BROTLI_HC_ADJUST_TABLE_INDEX(table, offset);
*bits2 = BROTLI_HC_GET_BITS(table);
*value2 = BROTLI_HC_GET_VALUE(table);
All uses of the HuffmanCode have been updated appropriately.
* decode: add alternative accessors for HuffmanCode on Arm AArch32
Stephen Kyle