Method pow5

Source/external/fast_float.h:2395–2424

multiply as if by 5 raised to a power.

  // multiply as if by 5 raised to a power.
  FASTFLOAT_CONSTEXPR20 bool pow5(uint32_t exp) noexcept {
	// multiply by a power of 5
	size_t large_length = sizeof(large_power_of_5) / sizeof(limb);
	limb_span large = limb_span(large_power_of_5, large_length);
	while (exp >= large_step) {
	  FASTFLOAT_TRY(large_mul(vec, large));
	  exp -= large_step;
	}
#ifdef FASTFLOAT_64BIT_LIMB
	uint32_t small_step = 27;
	limb max_native = 7450580596923828125UL;
#else
	uint32_t small_step = 13;
	limb max_native = 1220703125U;
#endif
	while (exp >= small_step) {
	  FASTFLOAT_TRY(small_mul(vec, max_native));
	  exp -= small_step;
	}
	if (exp != 0) {
	  // Work around clang bug https://godbolt.org/z/zedh7rrhc
	  // This is similar to https://github.com/llvm/llvm-project/issues/47746,
	  // except the workaround described there don't work here
	  FASTFLOAT_TRY(
		small_mul(vec, limb(((void)small_power_of_5[0], small_power_of_5[exp])))
	  );
	}

	return true;
  }

  // multiply as if by 10 raised to a power.
  FASTFLOAT_CONSTEXPR20 bool pow10(uint32_t exp) noexcept {