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/*
* upb - a minimalist implementation of protocol buffers.
*
* Copyright (c) 2011 Google Inc. See LICENSE for details.
* Author: Josh Haberman <jhaberman@gmail.com>
*/
#include "upb/pb/varint.h"
// Given an encoded varint v, returns an integer with a single bit set that
// indicates the end of the varint. Subtracting one from this value will
// yield a mask that leaves only bits that are part of the varint. Returns
// 0 if the varint is unterminated.
INLINE uint64_t upb_get_vstopbit(uint64_t v) {
uint64_t cbits = v | 0x7f7f7f7f7f7f7f7fULL;
return ~cbits & (cbits+1);
}
INLINE uint64_t upb_get_vmask(uint64_t v) { return upb_get_vstopbit(v) - 1; }
upb_decoderet upb_vdecode_max8_massimino(upb_decoderet r) {
uint64_t b;
memcpy(&b, r.p, sizeof(b));
uint64_t stop_bit = upb_get_vstopbit(b);
b = (b & 0x7f7f7f7f7f7f7f7fULL) & (stop_bit - 1);
b += b & 0x007f007f007f007fULL;
b += 3 * (b & 0x0000ffff0000ffffULL);
b += 15 * (b & 0x00000000ffffffffULL);
if (stop_bit == 0) {
// Error: unterminated varint.
upb_decoderet err_r = {(void*)0, 0};
return err_r;
}
upb_decoderet my_r = {r.p + ((__builtin_ctzll(stop_bit) + 1) / 8),
r.val | (b << 7)};
return my_r;
}
upb_decoderet upb_vdecode_max8_wright(upb_decoderet r) {
uint64_t b;
memcpy(&b, r.p, sizeof(b));
uint64_t stop_bit = upb_get_vstopbit(b);
b &= (stop_bit - 1);
b = ((b & 0x7f007f007f007f00) >> 1) | (b & 0x007f007f007f007f);
b = ((b & 0xffff0000ffff0000) >> 2) | (b & 0x0000ffff0000ffff);
b = ((b & 0xffffffff00000000) >> 4) | (b & 0x00000000ffffffff);
if (stop_bit == 0) {
// Error: unterminated varint.
upb_decoderet err_r = {(void*)0, 0};
return err_r;
}
upb_decoderet my_r = {r.p + ((__builtin_ctzll(stop_bit) + 1) / 8),
r.val | (b << 14)};
return my_r;
}
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