numberparsing_defs.h

#ifndef SIMDJSON_FALLBACK_NUMBERPARSING_DEFS_H
#define SIMDJSON_FALLBACK_NUMBERPARSING_DEFS_H
 
#ifndef SIMDJSON_CONDITIONAL_INCLUDE
#include "simdjson/fallback/base.h"
#include "simdjson/internal/numberparsing_tables.h"
#endif // SIMDJSON_CONDITIONAL_INCLUDE
 
#include <cstring>
 
#ifdef JSON_TEST_NUMBERS // for unit testing
void found_invalid_number(const uint8_t *buf);
void found_integer(int64_t result, const uint8_t *buf);
void found_unsigned_integer(uint64_t result, const uint8_t *buf);
void found_float(double result, const uint8_t *buf);
#endif
 
namespace simdjson {
namespace fallback {
namespace numberparsing {
 
// credit: https://johnnylee-sde.github.io/Fast-numeric-string-to-int/
static simdjson_inline uint32_t parse_eight_digits_unrolled(const char *chars) {
  uint64_t val;
  memcpy(&val, chars, sizeof(uint64_t));
  val = (val & 0x0F0F0F0F0F0F0F0F) * 2561 >> 8;
  val = (val & 0x00FF00FF00FF00FF) * 6553601 >> 16;
  return uint32_t((val & 0x0000FFFF0000FFFF) * 42949672960001 >> 32);
}
 
static simdjson_inline uint32_t parse_eight_digits_unrolled(const uint8_t *chars) {
  return parse_eight_digits_unrolled(reinterpret_cast<const char *>(chars));
}
 
#if SIMDJSON_IS_32BITS // _umul128 for x86, arm
// this is a slow emulation routine for 32-bit
//
static simdjson_inline uint64_t __emulu(uint32_t x, uint32_t y) {
  return x * (uint64_t)y;
}
static simdjson_inline uint64_t _umul128(uint64_t ab, uint64_t cd, uint64_t *hi) {
  uint64_t ad = __emulu((uint32_t)(ab >> 32), (uint32_t)cd);
  uint64_t bd = __emulu((uint32_t)ab, (uint32_t)cd);
  uint64_t adbc = ad + __emulu((uint32_t)ab, (uint32_t)(cd >> 32));
  uint64_t adbc_carry = !!(adbc < ad);
  uint64_t lo = bd + (adbc << 32);
  *hi = __emulu((uint32_t)(ab >> 32), (uint32_t)(cd >> 32)) + (adbc >> 32) +
        (adbc_carry << 32) + !!(lo < bd);
  return lo;
}
#endif
 
simdjson_inline internal::value128 full_multiplication(uint64_t value1, uint64_t value2) {
  internal::value128 answer;
#if SIMDJSON_REGULAR_VISUAL_STUDIO || SIMDJSON_IS_32BITS
#if SIMDJSON_IS_ARM64
  // ARM64 has native support for 64-bit multiplications, no need to emultate
  answer.high = __umulh(value1, value2);
  answer.low = value1 * value2;
#else
  answer.low = _umul128(value1, value2, &answer.high); // _umul128 not available on ARM64
#endif // SIMDJSON_IS_ARM64
#else // SIMDJSON_REGULAR_VISUAL_STUDIO || SIMDJSON_IS_32BITS
  __uint128_t r = (static_cast<__uint128_t>(value1)) * value2;
  answer.low = uint64_t(r);
  answer.high = uint64_t(r >> 64);
#endif
  return answer;
}
 
} // namespace numberparsing
} // namespace fallback
} // namespace simdjson
 
#ifndef SIMDJSON_SWAR_NUMBER_PARSING
#if SIMDJSON_IS_BIG_ENDIAN
#define SIMDJSON_SWAR_NUMBER_PARSING 0
#else
#define SIMDJSON_SWAR_NUMBER_PARSING 1
#endif
#endif
 
#endif // SIMDJSON_FALLBACK_NUMBERPARSING_DEFS_H