137 lines
3.1 KiB
C++
137 lines
3.1 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x86-family/float.cpp
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Handles saving and restoration of floating point numbers.
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*******************************************************************************/
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#include <assert.h>
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#include <sortix/kernel/interrupt.h>
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#include <sortix/kernel/kernel.h>
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#include <sortix/kernel/thread.h>
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#include "float.h"
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namespace Sortix {
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namespace Float {
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static Thread* fputhread;
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bool fpu_is_enabled = false;
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static inline void InitFPU()
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{
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asm volatile ("fninit");
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}
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static inline void SaveState(uint8_t* dest)
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{
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assert( (((unsigned long) dest) & (16UL-1UL)) == 0 );
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asm volatile ("fxsave (%0)" : : "r"(dest));
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}
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static inline void LoadState(const uint8_t* src)
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{
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assert( (((unsigned long) src) & (16UL-1UL)) == 0 );
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asm volatile ("fxrstor (%0)" : : "r"(src));
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}
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void Yield()
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{
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Thread* thread = CurrentThread();
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Interrupt::Disable();
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bool fpu_was_enabled = fpu_is_enabled;
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// The FPU contains the registers for this thread.
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if ( fputhread == thread )
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{
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if ( !fpu_was_enabled )
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EnableFPU();
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SaveState(thread->fpuenvaligned);
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fputhread = NULL;
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DisableFPU();
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}
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// This thread has used the FPU once.
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else if ( thread->fpuinitialized )
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{
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// Nothing needs to be done, the FPU is owned by another thread and the
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// FPU registers are already stored in the thread structure.
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}
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// This thread has never used the FPU and needs its registers initialized.
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else
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{
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if ( !fpu_was_enabled )
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EnableFPU();
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if ( fputhread )
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SaveState(fputhread->fpuenvaligned);
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InitFPU();
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SaveState(thread->fpuenvaligned);
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if ( fputhread )
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LoadState(fputhread->fpuenvaligned);
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if ( !fpu_was_enabled )
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DisableFPU();
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}
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Interrupt::Enable();
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}
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static void OnFPUAccess(CPU::InterruptRegisters* /*regs*/, void* /*user*/)
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{
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EnableFPU();
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Thread* thread = CurrentThread();
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if ( thread == fputhread )
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return;
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if ( fputhread )
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SaveState(fputhread->fpuenvaligned);
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fputhread = thread;
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if ( !thread->fpuinitialized )
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{
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InitFPU();
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thread->fpuinitialized = true;
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return;
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}
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LoadState(thread->fpuenvaligned);
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}
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void Init()
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{
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fputhread = CurrentThread();
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assert(fputhread);
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Interrupt::RegisterHandler(7, OnFPUAccess, NULL);
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}
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void NofityTaskExit(Thread* thread)
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{
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if ( fputhread == thread )
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fputhread = NULL;
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DisableFPU();
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}
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} // namespace Float
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} // namespace Sortix
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