Source file src/pkg/hash/crc32/crc32_s390x.go

     1	// Copyright 2016 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 crc32
     6	
     7	const (
     8		vxMinLen    = 64
     9		vxAlignMask = 15 // align to 16 bytes
    10	)
    11	
    12	// hasVectorFacility reports whether the machine has the z/Architecture
    13	// vector facility installed and enabled.
    14	func hasVectorFacility() bool
    15	
    16	var hasVX = hasVectorFacility()
    17	
    18	// vectorizedCastagnoli implements CRC32 using vector instructions.
    19	// It is defined in crc32_s390x.s.
    20	//go:noescape
    21	func vectorizedCastagnoli(crc uint32, p []byte) uint32
    22	
    23	// vectorizedIEEE implements CRC32 using vector instructions.
    24	// It is defined in crc32_s390x.s.
    25	//go:noescape
    26	func vectorizedIEEE(crc uint32, p []byte) uint32
    27	
    28	func archAvailableCastagnoli() bool {
    29		return hasVX
    30	}
    31	
    32	var archCastagnoliTable8 *slicing8Table
    33	
    34	func archInitCastagnoli() {
    35		if !hasVX {
    36			panic("not available")
    37		}
    38		// We still use slicing-by-8 for small buffers.
    39		archCastagnoliTable8 = slicingMakeTable(Castagnoli)
    40	}
    41	
    42	// archUpdateCastagnoli calculates the checksum of p using
    43	// vectorizedCastagnoli.
    44	func archUpdateCastagnoli(crc uint32, p []byte) uint32 {
    45		if !hasVX {
    46			panic("not available")
    47		}
    48		// Use vectorized function if data length is above threshold.
    49		if len(p) >= vxMinLen {
    50			aligned := len(p) & ^vxAlignMask
    51			crc = vectorizedCastagnoli(crc, p[:aligned])
    52			p = p[aligned:]
    53		}
    54		if len(p) == 0 {
    55			return crc
    56		}
    57		return slicingUpdate(crc, archCastagnoliTable8, p)
    58	}
    59	
    60	func archAvailableIEEE() bool {
    61		return hasVX
    62	}
    63	
    64	var archIeeeTable8 *slicing8Table
    65	
    66	func archInitIEEE() {
    67		if !hasVX {
    68			panic("not available")
    69		}
    70		// We still use slicing-by-8 for small buffers.
    71		archIeeeTable8 = slicingMakeTable(IEEE)
    72	}
    73	
    74	// archUpdateIEEE calculates the checksum of p using vectorizedIEEE.
    75	func archUpdateIEEE(crc uint32, p []byte) uint32 {
    76		if !hasVX {
    77			panic("not available")
    78		}
    79		// Use vectorized function if data length is above threshold.
    80		if len(p) >= vxMinLen {
    81			aligned := len(p) & ^vxAlignMask
    82			crc = vectorizedIEEE(crc, p[:aligned])
    83			p = p[aligned:]
    84		}
    85		if len(p) == 0 {
    86			return crc
    87		}
    88		return slicingUpdate(crc, archIeeeTable8, p)
    89	}
    90	

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