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//
// fpu.c
//
// Floating point unit
//
// Copyright (C) 2002 Michael Ringgaard. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// 3. Neither the name of the project nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
#include <os/krnl.h>
struct interrupt fpuintr;
struct interrupt fpuxcpt;
void fpu_enable(struct fpu *state) {
// Turn on access to FPU
set_cr0(get_cr0() & ~(CR0_EM | CR0_TS));
if (state) {
// Restore FPU state
__asm {
mov eax, state
frstor [eax]
}
} else {
// Initialize FPU
__asm {
fnclex
fninit
}
}
}
void fpu_disable(struct fpu *state) {
// Save FPU state
if (state) {
__asm {
mov eax, state
fnsave [eax]
}
}
// Disable acces to FPU
set_cr0(get_cr0() | CR0_EM);
}
int fpu_trap_handler(struct context *ctxt, void *arg) {
struct thread *t = self();
if (t->flags & THREAD_FPU_USED) {
fpu_enable(&t->fpustate);
t->flags |= THREAD_FPU_ENABLED;
} else {
fpu_enable(NULL);
t->flags |= THREAD_FPU_ENABLED | THREAD_FPU_USED;
}
return 0;
}
int fpu_npx_handler(struct context *ctxt, void *arg) {
panic("floating point processor fault");
return 0;
}
void init_fpu() {
register_interrupt(&fpuintr, INTR_FPU, fpu_trap_handler, NULL);
register_interrupt(&fpuxcpt, INTR_NPX, fpu_npx_handler, NULL);
set_cr0(get_cr0() | CR0_EM | CR0_NE);
}