Device and method for performing conditional bitwise set/clear/toggle manipulations in a general purpose register
View Patent ↗A device and a method for performing bitwise manipulation is provided. Multiple bitwise logic circuits are coupled to an instruction decoder, a register array and a rotator. Each bitwise logic circuit includes input multiplexers connected to an output multiplexer. The instruction decoder receives a bit manipulation instruction and sends to each corresponding input multiplexer a control signal based on a type of the instruction. Each input multiplexer of each bitwise logic circuit receives a control signal, a constant signal that has a value that is indifferent to the value of the mask, and a mask affected signal that has a value that is responsive to a value of an associated mask bit. Each input multiplexer selects between the constant signal and the mask affected signal based on the control signal, and outputs a selected signal. Each output multiplexer receives selected signals from each of the corresponding input multiplexers, and elects between the selected signal based on a value of an associated manipulated register bit and based on a value an associated control register bit.
1. A device, comprising:
an instruction decoder configured to:
receive a bit manipulation instruction; and
send a set of control signals based on a type of the bit manipulation instruction; and
multiple bitwise logic circuits, each bitwise logic circuit being coupled to the instruction decoder, wherein:
each bitwise logic circuit comprises one or more input multiplexers, each input multiplexer including a control input coupled to the instruction decoder a first data input, a second data input, and a data output coupled to an output multiplexer; and
each bitwise logic circuit is associated with manipulated register bits, mask bits, and control register bits that are different from other manipulated register bits, other mask bits, and other control register bits associated with each other bitwise logic circuit;
wherein each input multiplexer of each bitwise logic circuit is configured to:
receive one of the control signals at the control input, receive a constant signal at the first data input, wherein the constant signal has a value that is indifferent to a value of a mask, and receive a mask affected signal at the second data input, wherein the mask affected signal has a value that is responsive to a value of an associated mask bit;
select between the constant signal and the mask affected signal based on the control signal; and
output a selected signal; and
wherein each output multiplexer is configured to:
receive the selected signal from each of the input multiplexers;
select between the selected signals based on a value of the associated manipulated register bits and based on a value of the associated control register bits; and
output an output signal.
2. The device according to claim 1 , further comprising a rotator configured to rotate, by a shift factor indicated by the bit manipulation instruction, a content of a control register to provide to each bitwise logic circuit an associated control logic circuit bit.
3. The device according to claim 1 , wherein:
the instruction decoder is further configured to generate a different set of control signals per each type of bit manipulation instruction;
the types of the bit manipulation instructions comprise a bit toggle instruction; and
each bitwise logic circuit is configured to selectively toggle the associated manipulated register bit based on a value of the associated control register bit.
4. The device according to claim 1 , wherein:
the instruction decoder is configured to generate a different set of control signals per each type of the bit manipulation instruction;
the types of the bit manipulation instructions comprise a bit set instruction; and
each bitwise logic circuit is configured to selectively set an associated manipulated register bit based on a value of the associated control register bit.
5. The device according to claim 1 , wherein:
at least one input multiplexer of each bitwise logic circuit is configured to receive a mask affected signal that comprises a value that equals a value of the associated mask bit; and
at least one other input multiplexer of each bitwise logic circuit is configured to receive a mask affected signal that comprises a value that equals an inverted value of the associated mask bit.
6. The device according to claim 1 , wherein:
a first input multiplexer and a second input multiplexer of each bitwise logic circuit are configured to:
receive a mask affected signal that comprises a value that equals a value of the associated mask bit; and
receive a constant signal that equals zero; and
a third input multiplexer and a fourth input multiplexer of each bitwise logic circuit are configured to:
receive a mask affected signal that comprises a value that equals an inverted value of the associated mask bit; and
receive a constant signal that equals one.
7. The device according to claim 1 , wherein a respective four input multiplexers of each bitwise logic circuit are configured to:
select a set of signals that equals zero, the associated mask bit, one, and one, if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is set instruction;
select a set of signals that equals the associated mask bit, zero, one, and one, if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is reset instruction;
select a set of signals that equals zero, zero, one, and an inverted value of the associated mask bit, if the bit manipulation instruction is a reset associated manipulated register bit if associated control bit is set instruction; and
select a set of signals that equals zero, zero, the inverted value of the associated mask bit, and one, if the bit manipulation instruction is a reset associated manipulated register bit if associated control bit is reset instruction.
8. The device according to claim 1 , wherein a respective four input multiplexers of each bitwise logic circuit are configured to:
select a set of signals that equals zero, the associated mask bit, one, and an inverted value of the associated mask bit, if the bit manipulation instruction is a toggle associated manipulated register bit if associated control bit is set instruction; and
select a set of signals that equals the associated mask bit, zero, the inverted value of the associated mask bit, and one, if the bit manipulation instruction is a toggle associated manipulated register bit if associated control bit is reset instruction.
9. The device according to claim 1 , wherein the instruction decoder is configured to generate mask bits based on a mask indicator included in the bit manipulation instruction.
10. The device according to claim 1 , further comprising:
a bit selection unit that is coupled to the instruction decoder, to a register array, and to each bitwise logic circuit, wherein:
the instruction decoder is configured to send selection signals to the bit selection unit based on the bit manipulation instruction; and
the bit selection unit is configured to:
send, based on the selection signals, associated manipulated register bits to the bitwise logic circuits; and
send the control register bits to a rotator.
11. The device according to claim 1 , wherein the instruction decoder is further configured to:
receive a bit manipulation instruction that comprises at least one mask identifier, a shift factor identifier, a control register identifier, a manipulated register identifier and a bit manipulation instruction type identifier;
send to each input multiplexer of each bitwise logic circuit the control signal based on the bit manipulation instruction type identifier;
send to a rotator an instruction to rotate a content of a control register based on the shift factor identifier; and
send selection signals to a bit selection unit based on the control register identifier and the manipulated register identifier.
12. A device, comprising:
a fetch unit configured to fetch a bit manipulation instruction, the bit manipulation instruction comprising at least one mask identifier, a shift factor identifier, a control register identifier, a manipulated register identifier, and a bit manipulation instruction type identifier;
an instruction decoder configured to:
receive from the fetch unit the bit manipulation instruction;
send a control signal based on the bit manipulation instruction type identifier to each input multiplexer of a plurality of input multiplexers of each bitwise logic circuit of a plurality of bitwise logic circuits of the device;
send to a rotator an instruction to rotate a content of the control register based on the shift factor identifier; and
send selection signals to a bit selection unit based on the control register identifier and manipulated register identifier; and
an execution unit that comprises the plurality of bitwise logic circuits, the bit selection unit, and the rotator, wherein the execution unit is configured to complete an execution of the bit manipulation instruction based on control signals sent by the instruction decoder.
13. A method for performing bitwise manipulation, the method comprising:
receiving, by an instruction decoder, a bit manipulation instruction;
generating, by the instruction decoder, control signals based on a type of the bit manipulation instruction, wherein the instruction decoder is coupled to multiple bitwise logic circuits;
sending, to each input multiplexer of a plurality of input multiplexers of each bitwise logic circuit of a plurality of bitwise logic circuits, one control signal of the control signals;
wherein each bitwise logic circuits is associated with different control register bits;
selecting, by each input multiplexer, and based on the associated control signal that is received by each input multiplexer, between a constant signal that has a value that is indifferent to the value of a mask, and a mask affected signal that has a value that is responsive to a value of an associated mask bit, to provide a selected signal;
sending, for each bitwise logic circuit, the selected signals from each input multiplexer to an output multiplexer that belongs to the same bitwise logic circuit;
selecting, by each output multiplexer a selected signal to provide an output signal; wherein the selecting is responsive to a value of an associated manipulated register bit and to a value of an associated control register bit; and
outputting an output signal that reflects the selection.
14. The method according to claim 13 further comprising:
rotating, by a rotator that is coupled to the instruction decoder, and by a shift factor indicated by the bit manipulation instruction, a content of a control register; and
providing to each bitwise logic circuit an associated control logic circuit bit.
15. The method according to claim 13 further comprising,
selectively toggling manipulated register bits, by the multiple bitwise logic circuits, based on a value of the associated control register bit if the bit manipulation instruction type is a bit toggle instruction.
16. The method according to claim 13 further comprising:
providing, to at least one input multiplexer of each bitwise logic circuit, a mask affected signal that has a value that equals a value of the associated mask bit; and
providing, to at least one other input multiplexer of each bitwise logic circuit, a mask affected signal that has a value that equals an inverted value of the associated mask bit.
17. The method according to claim 13 further comprising:
providing, to two input multiplexers of each bitwise logic circuit, a mask affected signal that has a value that equals a value of the associated mask bit; and
providing, two to other input multiplexers of each bitwise logic circuit, a mask affected signal that has a value that equals an inverted value of the associated mask bit.
18. The method according to claim 13 further comprising:
selecting a set of signals that equals zero, the associated mask bit, one, and one, if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is set instruction;
selecting a set of signals that equals the associated mask bit, zero, one, and one, if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is reset instruction;
selecting a set of signals that equals zero, zero, one, and an inverted value of the associated mask bit, if the bit manipulation instruction is a reset associated manipulated register bit if associated control bit is set instruction; and
selecting a set of signals that equals zero, zero, the inverted value of the associated mask bit, and one, if the bit manipulation instruction is a reset associated manipulated register bit if associated control bit is reset instruction.
19. The method according to claim 12 further comprising:
selecting a set of signals that equals zero, the associated mask bit, one, and an inverted value of the associated mask bit, if the bit manipulation instruction is a toggle associated manipulated register bit if associated control bit is set instruction;
selecting a set of signals that equals, the associated mask bit, zero, the inverted value of the associated mask bit, and one, if the bit manipulation instruction is a toggle associate manipulated register bit if associated control bit is reset instruction;
selecting a set of signals that equals zero, the associated mask bit, one, and one, if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is set instruction;
selecting a set of signals that equals the associated mask bit, zero, one, and one if the bit manipulation instruction is a set associated manipulated register bit if associated control bit is reset instruction;
selecting a set of signals that equals zero, the associated mask bit, one, and the inverted value of the associated mask bit, if the bit manipulation instruction is a toggle associated manipulated register bit if associated control bit is set instruction; and
selecting a set of signals that equals the associated mask bit, zero, the inverted value of the associated mask bit, and one, if the bit manipulation instruction is a toggle associated manipulated register bit if associated control bit is reset instruction.
20. The method according to claim 13 further comprising:
receiving, by the instruction decoder, a bit manipulation instruction that comprises at least one mask identifier, a shift factor identifier, a control register identifier, a manipulated register identifier and a bit manipulation instruction type identifier;
sending, by the instruction decoder to each input multiplexer of each bitwise logic circuit, the control signal based on the bit manipulation instruction type identifier;
sending, by the instruction decoder to the rotator, an instruction to rotate a content of a control register based on the shift factor identifier; and
sending, by the instruction decoder, selection signals to a bit selection unit based on the control register identifier and manipulated register identifier.