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Register file
A register file is an array of addressable registers which has two or more ports that allow concurrent reading and writing of registers in the array. Reading is nondestructive, meaning that the act of reading does not alter the stored data.
Each port is either a write port or a read port, with input and output signals relevant to the port function. All ports have address inputs that specify the register to be accessed. Write ports also have data inputs that specify the value to be written to the register, and a write enable input that allows the data to be written. Read ports have data outputs that convey the register's output value.
Register files are used in a variety of applications, including as processor registers in central processing units (CPUs), as data memory in FIFOs, and in hardware accelerators.
The instruction set architecture of a CPU will almost always define a set of registers which are used to stage data between memory and the functional units on the chip. The register file is part of the architecture and visible to the programmer, as opposed to the concept of transparent caches. In simpler CPUs, these architectural registers correspond one-for-one to the entries in a physical register file (PRF) within the CPU. More complicated CPUs use register renaming, so that the mapping of which physical entry stores a particular architectural register changes dynamically during execution.
Register banking is the method of using a single name to access multiple different physical registers depending on the operating mode.
Register files may be clubbed together as register banks. A processor may have more than one register bank.
ARM processors have both banked and unbanked registers. While all modes always share the same physical registers for the first eight general-purpose registers (GPR), R0 to R7, the physical register which the banked registers, R8 to R14, point to depends on the operating mode the processor is in. Notably, Fast Interrupt Request (FIQ) mode has its own bank of registers for R8 to R12, with the architecture also providing a private stack pointer (R13) for every interrupt mode.
x86 processors use context switching and fast interrupts for switching between instruction, decoder, GPRs and register files, if there is more than one, before the instruction is issued, but this only exists on processors that support superscalar execution. However, context switching is a totally different mechanism to ARM's register bank within the registers.
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Register file AI simulator
(@Register file_simulator)
Register file
A register file is an array of addressable registers which has two or more ports that allow concurrent reading and writing of registers in the array. Reading is nondestructive, meaning that the act of reading does not alter the stored data.
Each port is either a write port or a read port, with input and output signals relevant to the port function. All ports have address inputs that specify the register to be accessed. Write ports also have data inputs that specify the value to be written to the register, and a write enable input that allows the data to be written. Read ports have data outputs that convey the register's output value.
Register files are used in a variety of applications, including as processor registers in central processing units (CPUs), as data memory in FIFOs, and in hardware accelerators.
The instruction set architecture of a CPU will almost always define a set of registers which are used to stage data between memory and the functional units on the chip. The register file is part of the architecture and visible to the programmer, as opposed to the concept of transparent caches. In simpler CPUs, these architectural registers correspond one-for-one to the entries in a physical register file (PRF) within the CPU. More complicated CPUs use register renaming, so that the mapping of which physical entry stores a particular architectural register changes dynamically during execution.
Register banking is the method of using a single name to access multiple different physical registers depending on the operating mode.
Register files may be clubbed together as register banks. A processor may have more than one register bank.
ARM processors have both banked and unbanked registers. While all modes always share the same physical registers for the first eight general-purpose registers (GPR), R0 to R7, the physical register which the banked registers, R8 to R14, point to depends on the operating mode the processor is in. Notably, Fast Interrupt Request (FIQ) mode has its own bank of registers for R8 to R12, with the architecture also providing a private stack pointer (R13) for every interrupt mode.
x86 processors use context switching and fast interrupts for switching between instruction, decoder, GPRs and register files, if there is more than one, before the instruction is issued, but this only exists on processors that support superscalar execution. However, context switching is a totally different mechanism to ARM's register bank within the registers.