From d493500abc6def6b62d664990ed821e0a836a6cf Mon Sep 17 00:00:00 2001 From: Josh Haberman Date: Thu, 24 Jul 2014 09:04:46 -0700 Subject: Sync from Google-internal development. --- upb/pb/decoder.int.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'upb/pb/decoder.int.h') diff --git a/upb/pb/decoder.int.h b/upb/pb/decoder.int.h index d0f12cc..9b35b70 100644 --- a/upb/pb/decoder.int.h +++ b/upb/pb/decoder.int.h @@ -147,6 +147,35 @@ void upb_pbdecoder_freejit(mgroup *group); // RET) for branching to when we find an appropriate ENDGROUP tag. #define DISPATCH_ENDMSG 0 +// It's important to use this invalid wire type instead of 0 (which is a valid +// wire type). +#define NO_WIRE_TYPE 0xff + +// The dispatch table layout is: +// [field number] -> [ 48-bit offset ][ 8-bit wt2 ][ 8-bit wt1 ] +// +// If wt1 matches, jump to the 48-bit offset. If wt2 matches, lookup +// (UPB_MAX_FIELDNUMBER + fieldnum) and jump there. +// +// We need two wire types because of packed/non-packed compatibility. A +// primitive repeated field can use either wire type and be valid. While we +// could key the table on fieldnum+wiretype, the table would be 8x sparser. +// +// Storing two wire types in the primary value allows us to quickly rule out +// the second wire type without needing to do a separate lookup (this case is +// less common than an unknown field). +UPB_INLINE uint64_t upb_pbdecoder_packdispatch(uint64_t ofs, uint8_t wt1, + uint8_t wt2) { + return (ofs << 16) | (wt2 << 8) | wt1; +} + +UPB_INLINE void upb_pbdecoder_unpackdispatch(uint64_t dispatch, uint64_t *ofs, + uint8_t *wt1, uint8_t *wt2) { + *wt1 = (uint8_t)dispatch; + *wt2 = (uint8_t)(dispatch >> 8); + *ofs = dispatch >> 16; +} + // All of the functions in decoder.c that return int32_t return values according // to the following scheme: // 1. negative values indicate a return code from the following list. -- cgit v1.2.3