// array. The top bits of this value are the remaining bits of the hash value that were not used
  // in the short hash. We saw that a mask of 0x7f would keep the 7-bit value 0x6f from a full
  // hashcode of 0x89abcdef. The imaginary `hash` value would then be the remaining top 25 bits,
  // 0x89abcd80. To this is added (or'd) the `next` value, which is an index within `entries`

	// heapAddrBits is the number of bits in a heap address. On
	// amd64, addresses are sign-extended beyond heapAddrBits. On
	// other arches, they are zero-extended.
	//
	// On most 64-bit platforms, we limit this to 48 bits based on a
	// combination of hardware and OS limitations.
	//
	// amd64 hardware limits addresses to 48 bits, sign-extended
	// to 64 bits. Addresses where the top 16 bits are not either

func getGOAMD64level() int32

const (
	// ecx bits
	cpuid_SSE3      = 1 << 0
	cpuid_PCLMULQDQ = 1 << 1
	cpuid_SSSE3     = 1 << 9
	cpuid_FMA       = 1 << 12
	cpuid_SSE41     = 1 << 19
	cpuid_SSE42     = 1 << 20
	cpuid_POPCNT    = 1 << 23
	cpuid_AES       = 1 << 25
	cpuid_OSXSAVE   = 1 << 27
	cpuid_AVX       = 1 << 28

	// ebx bits
	cpuid_BMI1     = 1 << 3
	cpuid_AVX2     = 1 << 5

(SETBC [1] cmp) && buildcfg.GOPPC64 <= 9 => (ISELZ [1] (MOVDconst [1]) cmp)
(SETBCR [1] cmp) && buildcfg.GOPPC64 <= 9 => (ISELZ [5] (MOVDconst [1]) cmp)

// The upper bits of the smaller than register values is undefined. Take advantage of that.
(AND <t> x:(MOVDconst [m]) n) && t.Size() <= 2 => (ANDconst [int64(int16(m))] n)

// Convert simple bit masks to an equivalent rldic[lr] if possible.

}

// bitconEncode returns the encoding of a bitcon used in logical instructions
// x is known to be a bitcon
// a bitcon is a sequence of n ones at low bits (i.e. 1<<n-1), right rotated
// by R bits, and repeated with period of 64, 32, 16, 8, 4, or 2.
// it is encoded in logical instructions with 3 bitfields
// N (1 bit) : R (6 bits) : S (6 bits), where
// N=1           -- period=64
// N=0, S=0xxxxx -- period=32

		if n == nil {
			return *new(V), false
		}
		if n.isEntry {
			return n.entry().lookup(key, ht.keyEqual)
		}
		i = n.indirect()
	}
	panic("internal/concurrent.HashMapTrie: ran out of hash bits while iterating")
}

// LoadOrStore returns the existing value for the key if present.
// Otherwise, it stores and returns the given value.
// The loaded result is true if the value was loaded, false if stored.

		// bits after the first one bit.
		top := uint(x[i])
		top |= top >> 1
		top |= top >> 2
		top |= top >> 4
		top |= top >> 8
		top |= top >> 16
		top |= top >> 16 >> 16 // ">> 32" doesn't compile on 32-bit architectures
		return i*_W + bits.Len(top)
	}
	return 0
}

// trailingZeroBits returns the number of consecutive least significant zero
// bits of x.

func floatBits(f float64) uint64 {
	u := math.Float64bits(f)
	return bits.ReverseBytes64(u)
}

// encFloat encodes the floating point value (float32 float64) referenced by v.
func encFloat(i *encInstr, state *encoderState, v reflect.Value) {
	f := v.Float()
	if f != 0 || state.sendZero {
		bits := floatBits(f)
		state.update(i)
		state.encodeUint(bits)
	}
}

// “synchronizes before” the return of any Wait call that it unblocks.
//
// [the Go memory model]: https://go.dev/ref/mem
type WaitGroup struct {
	noCopy noCopy

	state atomic.Uint64 // high 32 bits are counter, low 32 bits are waiter count.
	sema  uint32
}

// Add adds delta, which may be negative, to the [WaitGroup] counter.
// If the counter becomes zero, all goroutines blocked on [WaitGroup.Wait] are released.

		if excess := len(b)*8 - c.N.BitLen(); excess > 0 {
			// Just to be safe, assert that this only happens for the one curve that
			// doesn't have a round number of bits.
			if excess != 0 && c.curve.Params().Name != "P-521" {
				panic("ecdsa: internal error: unexpectedly masking off bits")
			}
			b[0] >>= excess
		}

		// FIPS 186-4 makes us check k <= N - 2 and then add one.
		// Checking 0 < k <= N - 1 is strictly equivalent.