6d85de3419
This replaces SDL threads with real cooperative threads, which are less cpu intensive and allow priority scheduling. The backend for context switching is dependant on the host (sigaltstack/longjmp on Unix, Fibers on Windows). configure has options to force or disallow SDL threads. git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29327 a1c6a512-1295-4272-9138-f99709370657
98 lines
3.6 KiB
C
98 lines
3.6 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2005 by Thom Johansen
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* Copyright (C) 2010 by Thomas Martitz (Android-suitable core_sleep())
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*
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* Generic ARM threading support
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include <system.h>
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/*---------------------------------------------------------------------------
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* Start the thread running and terminate it if it returns
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*---------------------------------------------------------------------------
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*/
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static void __attribute__((naked,used)) start_thread(void)
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{
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/* r0 = context */
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asm volatile (
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"ldr sp, [r0, #32] \n" /* Load initial sp */
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"ldr r4, [r0, #40] \n" /* start in r4 since it's non-volatile */
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"mov r1, #0 \n" /* Mark thread as running */
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"str r1, [r0, #40] \n"
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"mov lr, pc \n" /* Call thread function */
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"bx r4 \n"
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); /* No clobber list - new thread doesn't care */
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thread_exit();
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}
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/* For startup, place context pointer in r4 slot, start_thread pointer in r5
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* slot, and thread function pointer in context.start. See load_context for
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* what happens when thread is initially going to run. */
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#define THREAD_STARTUP_INIT(core, thread, function) \
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({ (thread)->context.r[0] = (uint32_t)&(thread)->context, \
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(thread)->context.r[1] = (uint32_t)start_thread, \
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(thread)->context.start = (uint32_t)function; })
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/*---------------------------------------------------------------------------
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* Store non-volatile context.
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*---------------------------------------------------------------------------
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*/
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static inline void store_context(void* addr)
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{
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asm volatile(
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"stmia %0, { r4-r11, sp, lr } \n"
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: : "r" (addr)
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);
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}
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/*---------------------------------------------------------------------------
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* Load non-volatile context.
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*---------------------------------------------------------------------------
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*/
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static inline void load_context(const void* addr)
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{
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asm volatile(
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"ldr r0, [%0, #40] \n" /* Load start pointer */
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"cmp r0, #0 \n" /* Check for NULL */
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/* If not already running, jump to start */
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"ldmneia %0, { r0, pc } \n"
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"ldmia %0, { r4-r11, sp, lr } \n" /* Load regs r4 to r14 from context */
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: : "r" (addr) : "r0" /* only! */
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);
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}
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/*
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* this core sleep suspends the OS thread rockbox runs under, which greatly
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* reduces cpu usage (~100% to <10%)
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*
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* it returns when when the tick timer is called, other interrupt-like
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* events occur
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*
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* wait_for_interrupt is implemented in kernel-<platform>.c
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**/
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static inline void core_sleep(void)
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{
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enable_irq();
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wait_for_interrupt();
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}
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