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Diffstat (limited to 'src/core/lib/transport/chttp2/varint.h')
| -rw-r--r-- | src/core/lib/transport/chttp2/varint.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/src/core/lib/transport/chttp2/varint.h b/src/core/lib/transport/chttp2/varint.h new file mode 100644 index 0000000000..e4a0ae3c22 --- /dev/null +++ b/src/core/lib/transport/chttp2/varint.h @@ -0,0 +1,75 @@ +/* + * + * Copyright 2015-2016, Google Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * * Neither the name of Google Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + */ + +#ifndef GRPC_CORE_LIB_TRANSPORT_CHTTP2_VARINT_H +#define GRPC_CORE_LIB_TRANSPORT_CHTTP2_VARINT_H + +#include <grpc/support/port_platform.h> + +/* Helpers for hpack varint encoding */ + +/* length of a value that needs varint tail encoding (it's bigger than can be + bitpacked into the opcode byte) - returned value includes the length of the + opcode byte */ +uint32_t grpc_chttp2_hpack_varint_length(uint32_t tail_value); + +void grpc_chttp2_hpack_write_varint_tail(uint32_t tail_value, uint8_t* target, + uint32_t tail_length); + +/* maximum value that can be bitpacked with the opcode if the opcode has a + prefix + of length prefix_bits */ +#define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \ + ((uint32_t)((1 << (8 - (prefix_bits))) - 1)) + +/* length required to bitpack a value */ +#define GRPC_CHTTP2_VARINT_LENGTH(n, prefix_bits) \ + ((n) < GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \ + ? 1u \ + : grpc_chttp2_hpack_varint_length( \ + (n)-GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits))) + +#define GRPC_CHTTP2_WRITE_VARINT(n, prefix_bits, prefix_or, target, length) \ + do { \ + uint8_t* tgt = target; \ + if ((length) == 1u) { \ + (tgt)[0] = (uint8_t)((prefix_or) | (n)); \ + } else { \ + (tgt)[0] = \ + (prefix_or) | (uint8_t)GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits); \ + grpc_chttp2_hpack_write_varint_tail( \ + (n)-GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits), (tgt) + 1, (length)-1); \ + } \ + } while (0) + +#endif /* GRPC_CORE_LIB_TRANSPORT_CHTTP2_VARINT_H */ |