x86: add atomic primitives
parent
c3847487be
commit
582758e868
GPG Key ID:
EC22E476DC2D3D84
@ -0,0 +1,238 @@
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/* See the end of this file for copyright and license terms. */
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#pragma once
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#include <gay/types.h>
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/**
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* @brief Read an atom's current value.
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* You usually shouldn't need this function because all the other atomic
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* primitives return the value before the operation, and we are only really
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* interested in how values *compare* between operations.
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* Don't use `atom_read()` followed by another atomic operation, it defeats the
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* whole purpose of using atomics in the first place.
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*
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* @param atom Atom to read the value of
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* @return The atom's "current" value (at the time of reading it)
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*/
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inline int atom_read(const atom_t *atom)
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{
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return atom->_value;
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}
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/**
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* @brief Write a new value to an atom.
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*
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* @param atom Atom to write to
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* @param val New value
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_write(atom_t *atom, int val)
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{
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int eax;
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__asm__ volatile(
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" mov (%2), %0 \n"
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"1: lock \n"
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" cmpxchgl %1, (%2) \n"
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" jne 1b \n"
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: "=a"(eax)
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: "r"(val), "r"(&atom->_value)
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: "cc", "memory"
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);
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return eax;
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}
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/**
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* @brief Perform an atomic load/add/store.
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*
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* @param atom Atom to add to
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* @param val Value to add
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_add(atom_t *atom, int val)
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{
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__asm__ volatile(
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" lock \n"
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" xaddl %0, (%1) \n"
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: "+r"(val)
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return val;
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}
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/**
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* @brief Perform an atomic load/subtract/store.
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*
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* @param atom Atom to subtract from
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* @param val Value to subtract
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_sub(atom_t *atom, int val)
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{
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return atom_add(atom, -val);
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}
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/**
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* @brief Increment an atom by one.
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*
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* @param atom Atom to increment
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* @return `true` if the vale *after* the operation is nonzero
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*/
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inline bool atom_inc(atom_t *atom)
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{
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bool nonzero = false;
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__asm__ volatile(
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" lock \n"
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" incl (%1) \n"
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" setne %0 \n"
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: "+r"(nonzero) /* read+write to ensure the initial value isn't optimized out */
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return nonzero;
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}
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/**
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* @brief Decrement an atom by one.
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*
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* @param atom Atom to decrement
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* @return `true` if the value *after* the operation is nonzero
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*/
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inline bool atom_dec(atom_t *atom)
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{
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bool nonzero = false;
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__asm__ volatile(
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" lock \n"
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" decl (%1) \n"
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" setne %0 \n"
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: "+r"(nonzero) /* read+write to ensure the initial value isn't optimized out */
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return nonzero;
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}
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/**
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* @brief Perform an atomic bitwise AND and write the result back to the atom.
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*
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* @param atom Atom to perform the AND on
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* @param val Value to AND with
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_and(atom_t *atom, int val)
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{
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int eax;
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__asm__ volatile(
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" movl (%2), %0 \n" /* eax = atom->_value */
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"1: andl %0, %1 \n" /* val &= eax */
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" lock \n"
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" cmpxchgl %1, (%2) \n" /* if (atom->_value == eax) atom->_value = val */
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" jne 1b \n" /* else goto 1 */
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: "=a"(eax), "+r"(val)
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return eax;
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}
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/**
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* @brief Perform an atomic bitwise OR and write the result back to the atom.
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*
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* @param atom Atom to perform the OR on
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* @param val Value to OR with
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_or(atom_t *atom, int val)
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{
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int eax;
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__asm__ volatile(
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" movl (%2), %0 \n" /* eax = atom->_value */
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"1: orl %0, %1 \n" /* eax |= eax */
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" lock \n"
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" cmpxchgl %1, (%2) \n" /* if (atom->_value == eax) atom->_value = eax */
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" jne 1b \n" /* else goto 1 */
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: "=a"(eax), "+r"(val)
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return eax;
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}
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/**
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* @brief Perform an atomic bitwise XOR and write the result back to the atom.
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*
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* @param atom Atom to perform the XOR on
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* @param val Value to XOR with
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* @return The value of `atom` *before* the operation
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*/
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inline int atom_xor(atom_t *atom, int val)
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{
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int eax;
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__asm__ volatile(
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" movl (%2), %0 \n" /* eax = atom->_value */
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"1: xorl %0, %1 \n" /* eax ^= eax */
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" lock \n"
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" cmpxchgl %1, (%2) \n" /* if (atom->_value == eax) atom->_value = eax */
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" jne 1b \n" /* else goto 1 */
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: "=a"(eax), "+r"(val)
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: "r"(&atom->_value)
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: "cc", "memory"
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);
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return eax;
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}
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/**
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* @brief Atomically set a bit.
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*
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* @param atom Atom to set a bit of
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* @param pos Bit position (starting from 0 for the LSB)
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* @return `true` the bit was clear *before* the operation
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*/
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inline bool arch_atom_set_bit(atom_t *atom, int pos)
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{
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int mask = 1 << pos;
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int oldval = atom_or(atom, mask);
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return (oldval & mask) == 0;
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}
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/**
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* @brief Atomically clear a bit.
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*
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* @param atom Atom to clear a bit of
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* @param pos Bit position (starting from 0 for the LSB)
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* @return `true` if the bit was set *before* the operation
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*/
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inline bool arch_atom_clr_bit(atom_t *atom, int pos)
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{
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int mask = 1 << pos;
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int oldval = atom_and(atom, ~mask);
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return (oldval & mask) != 0;
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}
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/*
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* This file is part of GayBSD.
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* Copyright (c) 2021 fef <owo@fef.moe>.
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*
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* GayBSD is nonviolent software: you may only use, redistribute, and/or
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* modify it under the terms of the Cooperative Nonviolent Public License
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* (CNPL) as found in the LICENSE file in the source code root directory
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* or at <https://git.pixie.town/thufie/npl-builder>; either version 7
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* of the license, or (at your option) any later version.
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*
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* GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
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* permitted by applicable law. See the CNPL for details.
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*/
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@ -0,0 +1,216 @@
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/* See the end of this file for copyright and license terms. */
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#include <asm/common.h>
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/* int arch_atom_read(const atom_t *atom) */
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ASM_ENTRY(arch_atom_read)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %ecx
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mov (%ecx), %eax
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pop %ebp
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ret
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ASM_END(arch_atom_read)
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/* int arch_atom_write(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_write)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov 12(%ebp), %ecx
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mov (%edx), %eax
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1: lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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pop %ebp
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ret
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ASM_END(arch_atom_write)
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/* bool arch_atom_inc(atom_t *atom) */
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ASM_ENTRY(arch_atom_inc)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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lock
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incl (%edx)
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xor %eax, %eax
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setne %al
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pop %ebp
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ret
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ASM_END(arch_atom_inc)
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/* bool arch_atom_dec(atom_t *atom) */
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ASM_ENTRY(arch_atom_dec)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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lock
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decl (%edx)
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xor %eax, %eax
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setne %al
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pop %ebp
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ret
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ASM_END(arch_atom_dec)
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/* int arch_atom_add(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_add)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov 12(%ebp), %eax
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lock
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xaddl %eax, (%edx)
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pop %ebp
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ret
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ASM_END(arch_atom_add)
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/* int arch_atom_sub(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_sub)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov 12(%ebp), %eax
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/* there is no xsubl, so we add the two's complement */
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not %eax
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inc %eax
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lock
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xaddl %eax, (%edx)
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pop %ebp
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ret
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ASM_END(arch_atom_sub)
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/* int arch_atom_and(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_and)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov (%edx), %eax
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1: mov %eax, %ecx
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and 12(%ebp), %ecx
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lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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pop %ebp
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ret
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ASM_END(arch_atom_and)
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/* int arch_atom_or(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_or)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov (%edx), %eax
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1: mov %eax, %ecx
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and 12(%ebp), %ecx
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lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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pop %ebp
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ret
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ASM_END(arch_atom_or)
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/* int arch_atom_xor(atom_t *atom, int val) */
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ASM_ENTRY(arch_atom_xor)
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push %ebp
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mov %esp, %ebp
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mov 8(%ebp), %edx
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mov (%edx), %eax
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1: mov %eax, %ecx
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xor 12(%ebp), %ecx
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lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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pop %ebp
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ret
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ASM_END(arch_atom_xor)
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/* bool arch_atom_set_bit(atom_t *atom, int bit) */
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ASM_ENTRY(arch_atom_set_bit)
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push %ebp
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mov %esp, %ebp
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push %ebx
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mov 8(%ebp), %edx
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mov 12(%ebp), %ecx
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mov $1, %ebx
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shl %cl, %ebx
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mov (%edx), %eax
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1: mov %eax, %ecx
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or %ebx, %ecx
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lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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/* return true if bit was clear before */
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not %eax
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and %ebx, %eax
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shr %cl, %eax
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pop %ebx
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pop %ebp
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ret
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ASM_END(arch_atom_set_bit)
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/* bool arch_atom_clr_bit(atom_t *atom, int bit) */
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ASM_ENTRY(arch_atom_clr_bit)
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push %ebp
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mov %esp, %ebp
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push %ebx
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mov 8(%ebp), %edx
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mov 12(%ebp), %ecx
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mov $0xfffffffe, %ebx
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rol %cl, %ebx
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mov (%edx), %eax
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1: mov %eax, %ecx
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and %ebx, %ecx
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lock
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cmpxchgl %ecx, (%edx)
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jne 1b
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/* return true if bit was set before */
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not %ebx
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and %ebx, %eax
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shr %cl, %eax
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pop %ebx
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pop %ebp
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ret
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ASM_END(arch_atom_clr_bit)
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/*
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* This file is part of GayBSD.
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* Copyright (c) 2021 fef <owo@fef.moe>.
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*
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* GayBSD is nonviolent software: you may only use, redistribute, and/or
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* modify it under the terms of the Cooperative Nonviolent Public License
|
||||
* (CNPL) as found in the LICENSE file in the source code root directory
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* or at <https://git.pixie.town/thufie/npl-builder>; either version 7
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* of the license, or (at your option) any later version.
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*
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* GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
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* permitted by applicable law. See the CNPL for details.
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*/
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