Module fpu 

Floating-Point Unit and Vector context for RISC-V 64-bit

This module provides the FPU and Vector context structures for saving and restoring floating-point and vector register state during context switches.

FPU (F/D Extensions)

RISC-V uses the F (single-precision) and D (double-precision) extensions with 32 floating-point registers (f0-f31, each 64-bit for D extension) and fcsr control/status register.

Vector (V Extension)

RISC-V Vector extension provides 32 vector registers (v0-v31) with configurable VLEN (vector length). The actual size depends on the implementation. This module supports VLEN up to 256 bits (32 bytes per register, vlenb=32).

Modules

fpu_switch 🔒

Structs

FpuContext

FPU context for RISC-V 64-bit (F/D extensions)

VectorContext

Vector context for RISC-V 64-bit (V extension)

Constants

MAX_VLENB

Maximum vector length in bytes (VLEN / 8) supported by this implementation. This supports VLEN up to 256 bits (32 bytes per register). QEMU virt machine typically uses VLEN=128 (vlenb=16).

Functions

disable_fpu

Disable FPU access by setting sstatus.FS to Off.

disable_vector

Disable Vector extension access by setting sstatus.VS to Off.

enable_fpu

Enable FPU access by setting sstatus.FS to Initial state

enable_vector

Enable Vector extension access by setting sstatus.VS to Initial state

get_vlenb

Get the vector length in bytes (vlenb = VLEN / 8)

is_fpu_dirty

Check if the FPU state is marked Dirty in sstatus (FS == 0b11).

is_fpu_enabled

Check if FPU is enabled (sstatus.FS != Off)

is_vector_dirty

Check if the Vector state is marked Dirty in sstatus (VS == 0b11).

is_vector_enabled

Check if Vector extension is enabled (sstatus.VS != Off)

kernel_switch_in_user_fpu

Restore user FPU context when resuming a task in the kernel.

kernel_switch_out_user_fpu

Save user FPU context when switching away from a task in the kernel.

kernel_switch_out_user_vector

Handle user vector state on kernel switch-out.

mark_fpu_clean

Mark the FPU state as Clean in sstatus (FS = 0b10).

mark_vector_clean

Mark the Vector state as Clean in sstatus (VS = 0b10).