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package tpm2
import (
"fmt"
)
// Bitfield represents a TPM bitfield (i.e., TPMA_*) type.
type Bitfield interface {
// Length returns the length of the bitfield.
Length() int
}
// BitGetter represents a TPM bitfield (i.e., TPMA_*) type that can be read.
type BitGetter interface {
Bitfield
// GetReservedBit returns the value of the given reserved bit.
// If the bit is not reserved, returns false.
GetReservedBit(pos int) bool
}
// BitSetter represents a TPM bitfield (i.e., TPMA_*) type that can be written.
type BitSetter interface {
Bitfield
// GetReservedBit sets the value of the given reserved bit.
SetReservedBit(pos int, val bool)
}
func checkPos(pos int, len int) {
if pos >= len || pos < 0 {
panic(fmt.Errorf("bit %d out of range for %d-bit field", pos, len))
}
}
// bitfield8 represents an 8-bit bitfield which may have reserved bits.
// 8-bit TPMA_* types embed this one, and the reserved bits are stored in it.
type bitfield8 uint8
// Length implements the Bitfield interface.
func (bitfield8) Length() int {
return 8
}
// GetReservedBit implements the BitGetter interface.
func (r bitfield8) GetReservedBit(pos int) bool {
checkPos(pos, 8)
return r&(1<<pos) != 0
}
// SetReservedBit implements the BitSetter interface.
func (r *bitfield8) SetReservedBit(pos int, val bool) {
checkPos(pos, 8)
if val {
*r |= 1 << pos
} else {
*r &= ^(1 << pos)
}
}
// bitfield32 represents a 32-bit bitfield which may have reserved bits.
// 32-bit TPMA_* types embed this one, and the reserved bits are stored in it.
type bitfield32 uint32
// Length implements the Bitfield interface.
func (bitfield32) Length() int {
return 32
}
// GetReservedBit implements the BitGetter interface.
func (r bitfield32) GetReservedBit(pos int) bool {
checkPos(pos, 32)
return r&(1<<pos) != 0
}
// SetReservedBit implements the BitSetter interface.
func (r *bitfield32) SetReservedBit(pos int, val bool) {
checkPos(pos, 32)
if val {
*r |= 1 << pos
} else {
*r &= ^(1 << pos)
}
}
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