github.com/aloncn/graphics-go@v0.0.1/src/runtime/internal/atomic/atomic_arm.go (about)

     1  // Copyright 2009 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  // +build arm
     6  
     7  package atomic
     8  
     9  import (
    10  	"runtime/internal/sys"
    11  	"unsafe"
    12  )
    13  
    14  type spinlock struct {
    15  	v uint32
    16  }
    17  
    18  //go:nosplit
    19  func (l *spinlock) lock() {
    20  	for {
    21  		if Cas(&l.v, 0, 1) {
    22  			return
    23  		}
    24  	}
    25  }
    26  
    27  //go:nosplit
    28  func (l *spinlock) unlock() {
    29  	Store(&l.v, 0)
    30  }
    31  
    32  var locktab [57]struct {
    33  	l   spinlock
    34  	pad [sys.CacheLineSize - unsafe.Sizeof(spinlock{})]byte
    35  }
    36  
    37  func addrLock(addr *uint64) *spinlock {
    38  	return &locktab[(uintptr(unsafe.Pointer(addr))>>3)%uintptr(len(locktab))].l
    39  }
    40  
    41  // Atomic add and return new value.
    42  //go:nosplit
    43  func Xadd(val *uint32, delta int32) uint32 {
    44  	for {
    45  		oval := *val
    46  		nval := oval + uint32(delta)
    47  		if Cas(val, oval, nval) {
    48  			return nval
    49  		}
    50  	}
    51  }
    52  
    53  //go:noescape
    54  func Xadduintptr(ptr *uintptr, delta uintptr) uintptr
    55  
    56  //go:nosplit
    57  func Xchg(addr *uint32, v uint32) uint32 {
    58  	for {
    59  		old := *addr
    60  		if Cas(addr, old, v) {
    61  			return old
    62  		}
    63  	}
    64  }
    65  
    66  //go:nosplit
    67  func Xchguintptr(addr *uintptr, v uintptr) uintptr {
    68  	return uintptr(Xchg((*uint32)(unsafe.Pointer(addr)), uint32(v)))
    69  }
    70  
    71  //go:nosplit
    72  func Load(addr *uint32) uint32 {
    73  	return Xadd(addr, 0)
    74  }
    75  
    76  // Should be a built-in for unsafe.Pointer?
    77  //go:nosplit
    78  func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
    79  	return unsafe.Pointer(uintptr(p) + x)
    80  }
    81  
    82  //go:nosplit
    83  func Loadp(addr unsafe.Pointer) unsafe.Pointer {
    84  	return unsafe.Pointer(uintptr(Xadd((*uint32)(addr), 0)))
    85  }
    86  
    87  //go:nosplit
    88  func Storep1(addr unsafe.Pointer, v unsafe.Pointer) {
    89  	for {
    90  		old := *(*unsafe.Pointer)(addr)
    91  		if Casp1((*unsafe.Pointer)(addr), old, v) {
    92  			return
    93  		}
    94  	}
    95  }
    96  
    97  //go:nosplit
    98  func Store(addr *uint32, v uint32) {
    99  	for {
   100  		old := *addr
   101  		if Cas(addr, old, v) {
   102  			return
   103  		}
   104  	}
   105  }
   106  
   107  //go:nosplit
   108  func Cas64(addr *uint64, old, new uint64) bool {
   109  	var ok bool
   110  	addrLock(addr).lock()
   111  	if *addr == old {
   112  		*addr = new
   113  		ok = true
   114  	}
   115  	addrLock(addr).unlock()
   116  	return ok
   117  }
   118  
   119  //go:nosplit
   120  func Xadd64(addr *uint64, delta int64) uint64 {
   121  	var r uint64
   122  	addrLock(addr).lock()
   123  	r = *addr + uint64(delta)
   124  	*addr = r
   125  	addrLock(addr).unlock()
   126  	return r
   127  }
   128  
   129  //go:nosplit
   130  func Xchg64(addr *uint64, v uint64) uint64 {
   131  	var r uint64
   132  	addrLock(addr).lock()
   133  	r = *addr
   134  	*addr = v
   135  	addrLock(addr).unlock()
   136  	return r
   137  }
   138  
   139  //go:nosplit
   140  func Load64(addr *uint64) uint64 {
   141  	var r uint64
   142  	addrLock(addr).lock()
   143  	r = *addr
   144  	addrLock(addr).unlock()
   145  	return r
   146  }
   147  
   148  //go:nosplit
   149  func Store64(addr *uint64, v uint64) {
   150  	addrLock(addr).lock()
   151  	*addr = v
   152  	addrLock(addr).unlock()
   153  }
   154  
   155  //go:nosplit
   156  func Or8(addr *uint8, v uint8) {
   157  	// Align down to 4 bytes and use 32-bit CAS.
   158  	uaddr := uintptr(unsafe.Pointer(addr))
   159  	addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
   160  	word := uint32(v) << ((uaddr & 3) * 8) // little endian
   161  	for {
   162  		old := *addr32
   163  		if Cas(addr32, old, old|word) {
   164  			return
   165  		}
   166  	}
   167  }
   168  
   169  //go:nosplit
   170  func And8(addr *uint8, v uint8) {
   171  	// Align down to 4 bytes and use 32-bit CAS.
   172  	uaddr := uintptr(unsafe.Pointer(addr))
   173  	addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
   174  	word := uint32(v) << ((uaddr & 3) * 8)    // little endian
   175  	mask := uint32(0xFF) << ((uaddr & 3) * 8) // little endian
   176  	word |= ^mask
   177  	for {
   178  		old := *addr32
   179  		if Cas(addr32, old, old&word) {
   180  			return
   181  		}
   182  	}
   183  }