context.c

Go to the documentation of this file.
00001 /*
00002  * Copyright (C) 2001-2005 by egnite Software GmbH. All rights reserved.
00003  *
00004  * Redistribution and use in source and binary forms, with or without
00005  * modification, are permitted provided that the following conditions
00006  * are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the copyright holders nor the names of
00014  *    contributors may be used to endorse or promote products derived
00015  *    from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
00018  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00019  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00020  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE
00021  * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00022  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00023  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
00024  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
00025  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00026  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
00027  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00028  * SUCH DAMAGE.
00029  *
00030  * For additional information see http://www.ethernut.de/
00031  *
00032  */
00033 
00034 /*
00035  * $Log: context.c,v $
00036  * Revision 1.6  2008/07/07 11:04:27  haraldkipp
00037  * Configurable ways of handling critical sections for ARM targets.
00038  *
00039  * Revision 1.5  2006/03/16 19:06:16  haraldkipp
00040  * Use link register to jump into thread and use dedicated routine to
00041  * jump into the idle thread. The way we did start the idle thread
00042  * before, jumping into the middle of NutThreadSwitch(), doesn't work
00043  * with optimized code.
00044  *
00045  * Revision 1.4  2006/03/16 15:25:00  haraldkipp
00046  * Changed human readable strings from u_char to char to stop GCC 4 from
00047  * nagging about signedness.
00048  *
00049  * Revision 1.3  2005/10/24 09:09:41  haraldkipp
00050  * Switch frame reduced.
00051  * NutThreadEntry included in the execution path.
00052  * The 'cc' globber had been removed from the context switching asm macro,
00053  * after Michael Fischer found out that this fixes a problem with optimized
00054  * compilation. Unfortunately, compiler optimized binaries still seem to
00055  * run unreliable.
00056  *
00057  * Revision 1.2  2005/08/02 17:46:45  haraldkipp
00058  * Major API documentation update.
00059  *
00060  * Revision 1.1  2005/07/26 18:10:48  haraldkipp
00061  * Moved from os/thread.c
00062  *
00063  * Revision 1.1  2005/05/27 17:16:40  drsung
00064  * Moved the file.
00065  *
00066  * Revision 1.4  2005/04/05 17:54:36  haraldkipp
00067  * Moved from user mode to system mode. Probably breaks the GBA port.
00068  *
00069  * Revision 1.3  2004/11/08 19:15:33  haraldkipp
00070  * Made assembly includes look nicer.
00071  * Changed mode from supervisory to user supervisory, which seems to work
00072  * with the GBA.
00073  * Skipped entry frame, because it simply confuses me. :-)
00074  *
00075  * Revision 1.2  2004/09/08 10:19:31  haraldkipp
00076  * Tyou's support for the ARM7
00077  *
00078  * Revision 1.1  2004/03/16 16:48:46  haraldkipp
00079  * Added Jan Dubiec's H8/300 port.
00080  *
00081  * Revision 1.2  2004/02/18 16:32:48  drsung
00082  * Bugfix in NutThreadCreate. Thanks to Mike Cornelius.
00083  *
00084  * Revision 1.1  2004/02/01 18:49:48  haraldkipp
00085  * Added CPU family support
00086  *
00087  */
00088 
00089 #include <cfg/os.h>
00090 
00091 #include <string.h>
00092 
00093 #include <sys/atom.h>
00094 #include <sys/heap.h>
00095 #include <sys/thread.h>
00096 
00101 
00102 
00110 typedef struct {
00111     u_long csf_cpsr;
00112     u_long csf_r4;
00113     u_long csf_r5;
00114     u_long csf_r6;
00115     u_long csf_r7;
00116     u_long csf_r8;
00117     u_long csf_r9;
00118     u_long csf_r10;
00119     u_long csf_r11;             /* AKA fp */
00120     u_long csf_lr;
00121 } SWITCHFRAME;
00122 
00128 typedef struct {
00129     u_long cef_r0;
00130     u_long cef_pc;
00131 } ENTERFRAME;
00132 
00136 static void NutThreadEntry(void) __attribute__ ((naked));
00137 void NutThreadEntry(void)
00138 {
00139     /* Load argument in r0 and jump to thread entry. */
00140     asm volatile ("ldmfd   sp!, {r0, lr}\n\tbx lr":::"r0", "lr");
00141 }
00142 
00143 
00155 void NutThreadSwitch(void) __attribute__ ((naked));
00156 void NutThreadSwitch(void)
00157 {
00158     /* Save CPU context. */
00159     asm volatile (              /* */
00160                      "@ Save context\n\t"       /* */
00161                      "stmfd   sp!, {r4-r11, lr}\n\t"    /* Save registers. */
00162                      "mrs     r4, cpsr\n\t"     /* Save status. */
00163                      "stmfd   sp!, {r4}\n\t"    /* */
00164                      "str     sp, %0"   /* Save stack pointer. */
00165                      ::"m" (runningThread->td_sp)       /* */
00166         );
00167 
00168     /* Select thread on top of the run queue. */
00169     runningThread = runQueue;
00170     runningThread->td_state = TDS_RUNNING;
00171 
00172     /* Restore context. */
00173     __asm__ __volatile__(       /* */
00174                             "@ Load context\n\t"        /* */
00175                             "ldr     sp, %0\n\t"        /* Restore stack pointer. */
00176                             "ldmfd   sp!, {r4}\n\t"     /* Get saved status... */
00177                             "bic     r4, r4, #0xC0" "\n\t"      /* ...enable interrupts */
00178                             "msr     spsr, r4\n\t"      /* ...and save in spsr. */
00179                             "ldmfd   sp!, {r4-r11, lr}\n\t"     /* Restore registers. */
00180                             "movs    pc, lr"    /* Restore status and return. */
00181                             ::"m"(runningThread->td_sp) /* */
00182         );
00183 #if defined(NUT_CRITICAL_NESTING) && !defined(NUT_CRITICAL_NESTING_STACK)
00184         critical_nesting_level = 0;
00185 #endif
00186 }
00187 
00208 HANDLE NutThreadCreate(char * name, void (*fn) (void *), void *arg, size_t stackSize)
00209 {
00210     u_char *threadMem;
00211     SWITCHFRAME *sf;
00212     ENTERFRAME *ef;
00213     NUTTHREADINFO *td;
00214 
00215     /*
00216      * Allocate stack and thread info structure in one block.
00217      * We sill setup the following layout:
00218      *
00219      * Upper memory addresses.
00220      *
00221      *              +--------------------+
00222      *              I                    I
00223      *              I   NUTTHREADINFO    I
00224      *              I                    I
00225      * td ->        +-----+--------------+ <- Stack top
00226      *              I     I              I
00227      *              I  T  I   ENTERFRAME I
00228      *              I  H  I              I
00229      * ef ->        I  R  +--------------+
00230      *              I  E  I              I    ^
00231      *              I  A  I  SWITCHFRAME I    I
00232      *              I  D  I              I    I  pop moves up
00233      * sf ->        I     +--------------+ <- Initial stack pointer
00234      *              I  S  I              I    I  push moves down
00235      *              I  T  I Application  I    I
00236      *              I  A  I Stack        I    V
00237      *              I  C  I              I
00238      *              I  K  I              I
00239      * threadMem -> +-----+--------------+ <- Stack bottom
00240      *
00241      * Lower memory addresses.
00242      */
00243     if ((threadMem = NutHeapAlloc(stackSize + sizeof(NUTTHREADINFO))) == 0) {
00244         return 0;
00245     }
00246     td = (NUTTHREADINFO *) (threadMem + stackSize);
00247     ef = (ENTERFRAME *) ((uptr_t) td - sizeof(ENTERFRAME));
00248     sf = (SWITCHFRAME *) ((uptr_t) ef - sizeof(SWITCHFRAME));
00249 
00250     /* 
00251      * Set predefined values at the stack bottom. May be used to detect
00252      * stack overflows.
00253      */
00254     *((u_long *) threadMem) = DEADBEEF;
00255     *((u_long *) (threadMem + 4)) = DEADBEEF;
00256     *((u_long *) (threadMem + 8)) = DEADBEEF;
00257     *((u_long *) (threadMem + 12)) = DEADBEEF;
00258 
00259     /*
00260      * Setup the entry frame to simulate C function entry.
00261      */
00262     ef->cef_pc = (uptr_t) fn;
00263     ef->cef_r0 = (uptr_t) arg;
00264 
00265     /*
00266      * Setup the switch frame.
00267      */
00268     sf->csf_lr = (uptr_t) NutThreadEntry;
00269     sf->csf_cpsr = I_BIT | F_BIT | ARM_MODE_SVC;
00270 
00271     /*
00272      * Initialize the thread info structure and insert it into the 
00273      * thread list and the run queue.
00274      */
00275     memcpy(td->td_name, name, sizeof(td->td_name) - 1);
00276     td->td_name[sizeof(td->td_name) - 1] = 0;
00277     td->td_state = TDS_READY;
00278     td->td_sp = (uptr_t) sf;
00279     td->td_priority = 64;
00280     td->td_memory = threadMem;
00281     td->td_timer = 0;
00282     td->td_queue = 0;
00283 
00284     NutEnterCritical();
00285     td->td_next = nutThreadList;
00286     nutThreadList = td;
00287     NutThreadAddPriQueue(td, (NUTTHREADINFO **) & runQueue);
00288 
00289     /*
00290      * If no thread is running, then this is the first thread ever 
00291      * created. In Nut/OS, the idle thread is created first.
00292      */
00293     if (runningThread == 0) {
00294         /* This will never return. */
00295         runningThread = runQueue;
00296         runningThread->td_state = TDS_RUNNING;
00297         /* Restore context. */
00298         __asm__ __volatile__(       /* */
00299                             "@ Load context\n\t"        /* */
00300                             "ldr     sp, %0\n\t"        /* Restore stack pointer. */
00301                             "ldmfd   sp!, {r4}\n\t"     /* Get saved status... */
00302                             "bic     r4, r4, #0xC0" "\n\t"      /* ...enable interrupts */
00303                             "msr     spsr, r4\n\t"      /* ...and save in spsr. */
00304                             "ldmfd   sp!, {r4-r11, lr}\n\t"     /* Restore registers. */
00305                             "movs    pc, lr"    /* Restore status and return. */
00306                             ::"m"(runningThread->td_sp) /* */
00307                             );
00308     }
00309 
00310     /*
00311      * If current context is not in front of the run queue (highest 
00312      * priority), then switch to the thread in front.
00313      */
00314     if (runningThread != runQueue) {
00315         runningThread->td_state = TDS_READY;
00316         NutThreadSwitch();
00317     }
00318     NutExitCritical();
00319 
00320     return td;
00321 }
00322 

© 2000-2007 by egnite Software GmbH - visit http://www.ethernut.de/