85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package ppc64asm
|
|
|
|
import (
|
|
"fmt"
|
|
"strings"
|
|
)
|
|
|
|
// A BitField is a bit-field in a 32-bit word.
|
|
// Bits are counted from 0 from the MSB to 31 as the LSB.
|
|
type BitField struct {
|
|
Offs uint8 // the offset of the left-most bit.
|
|
Bits uint8 // length in bits.
|
|
}
|
|
|
|
func (b BitField) String() string {
|
|
if b.Bits > 1 {
|
|
return fmt.Sprintf("[%d:%d]", b.Offs, int(b.Offs+b.Bits)-1)
|
|
} else if b.Bits == 1 {
|
|
return fmt.Sprintf("[%d]", b.Offs)
|
|
} else {
|
|
return fmt.Sprintf("[%d, len=0]", b.Offs)
|
|
}
|
|
}
|
|
|
|
// Parse extracts the bitfield b from i, and return it as an unsigned integer.
|
|
// Parse will panic if b is invalid.
|
|
func (b BitField) Parse(i uint32) uint32 {
|
|
if b.Bits > 32 || b.Bits == 0 || b.Offs > 31 || b.Offs+b.Bits > 32 {
|
|
panic(fmt.Sprintf("invalid bitfiled %v", b))
|
|
}
|
|
return (i >> (32 - b.Offs - b.Bits)) & ((1 << b.Bits) - 1)
|
|
}
|
|
|
|
// ParseSigned extracts the bitfield b from i, and return it as a signed integer.
|
|
// ParseSigned will panic if b is invalid.
|
|
func (b BitField) ParseSigned(i uint32) int32 {
|
|
u := int32(b.Parse(i))
|
|
return u << (32 - b.Bits) >> (32 - b.Bits)
|
|
}
|
|
|
|
// BitFields is a series of BitFields representing a single number.
|
|
type BitFields []BitField
|
|
|
|
func (bs BitFields) String() string {
|
|
ss := make([]string, len(bs))
|
|
for i, bf := range bs {
|
|
ss[i] = bf.String()
|
|
}
|
|
return fmt.Sprintf("<%s>", strings.Join(ss, "|"))
|
|
}
|
|
|
|
func (bs *BitFields) Append(b BitField) {
|
|
*bs = append(*bs, b)
|
|
}
|
|
|
|
// parse extracts the bitfields from i, concatenate them and return the result
|
|
// as an unsigned integer and the total length of all the bitfields.
|
|
// parse will panic if any bitfield in b is invalid, but it doesn't check if
|
|
// the sequence of bitfields is reasonable.
|
|
func (bs BitFields) parse(i uint32) (u uint32, Bits uint8) {
|
|
for _, b := range bs {
|
|
u = (u << b.Bits) | b.Parse(i)
|
|
Bits += b.Bits
|
|
}
|
|
return u, Bits
|
|
}
|
|
|
|
// Parse extracts the bitfields from i, concatenate them and return the result
|
|
// as an unsigned integer. Parse will panic if any bitfield in b is invalid.
|
|
func (bs BitFields) Parse(i uint32) uint32 {
|
|
u, _ := bs.parse(i)
|
|
return u
|
|
}
|
|
|
|
// Parse extracts the bitfields from i, concatenate them and return the result
|
|
// as a signed integer. Parse will panic if any bitfield in b is invalid.
|
|
func (bs BitFields) ParseSigned(i uint32) int32 {
|
|
u, l := bs.parse(i)
|
|
return int32(u) << (32 - l) >> (32 - l)
|
|
}
|