minmax.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import "unsafe"
     8  
     9  func strmin(x, y string) string {
    10  	if y < x {
    11  		return y
    12  	}
    13  	return x
    14  }
    15  
    16  func strmax(x, y string) string {
    17  	if y > x {
    18  		return y
    19  	}
    20  	return x
    21  }
    22  
    23  func fmin32(x, y float32) float32 { return fmin(x, y) }
    24  func fmin64(x, y float64) float64 { return fmin(x, y) }
    25  func fmax32(x, y float32) float32 { return fmax(x, y) }
    26  func fmax64(x, y float64) float64 { return fmax(x, y) }
    27  
    28  type floaty interface{ ~float32 | ~float64 }
    29  
    30  func fmin[F floaty](x, y F) F {
    31  	if y != y || y < x {
    32  		return y
    33  	}
    34  	if x != x || x < y || x != 0 {
    35  		return x
    36  	}
    37  	// x and y are both ±0
    38  	// if either is -0, return -0; else return +0
    39  	return forbits(x, y)
    40  }
    41  
    42  func fmax[F floaty](x, y F) F {
    43  	if y != y || y > x {
    44  		return y
    45  	}
    46  	if x != x || x > y || x != 0 {
    47  		return x
    48  	}
    49  	// x and y are both ±0
    50  	// if both are -0, return -0; else return +0
    51  	return fandbits(x, y)
    52  }
    53  
    54  func forbits[F floaty](x, y F) F {
    55  	switch unsafe.Sizeof(x) {
    56  	case 4:
    57  		*(*uint32)(unsafe.Pointer(&x)) |= *(*uint32)(unsafe.Pointer(&y))
    58  	case 8:
    59  		*(*uint64)(unsafe.Pointer(&x)) |= *(*uint64)(unsafe.Pointer(&y))
    60  	}
    61  	return x
    62  }
    63  
    64  func fandbits[F floaty](x, y F) F {
    65  	switch unsafe.Sizeof(x) {
    66  	case 4:
    67  		*(*uint32)(unsafe.Pointer(&x)) &= *(*uint32)(unsafe.Pointer(&y))
    68  	case 8:
    69  		*(*uint64)(unsafe.Pointer(&x)) &= *(*uint64)(unsafe.Pointer(&y))
    70  	}
    71  	return x
    72  }
    73
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