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jeremybenn |
/* uos.c. Microkernel for Or1ksim
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Copyright (C) 2000 Damjan Lampret
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Copyright (C) 2010 Embecosm Limited
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Contributor Damjan Lampret <lampret@opencores.org>
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Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
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This file is part of OpenRISC 1000 Architectural Simulator.
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This program is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along
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with this program. If not, see <http: www.gnu.org/licenses/>. */
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/* ----------------------------------------------------------------------------
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This code is commented throughout for use with Doxygen.
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--------------------------------------------------------------------------*/
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/* This file is part of test microkernel for OpenRISC 1000. */
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#include "support.h"
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#include "spr-defs.h"
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#include "uos.h"
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#include "ipc.h"
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#include "int.h"
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/* External functions prototypes */
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int tick_init(unsigned long period, void (* inf)(void));
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/* Pointers to contexts used by except_or32.S routines */
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unsigned long *task_context;
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unsigned long *kernel_context;
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/* TCBs for all tasks in the system */
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struct tcb tasks[MAX_TASKS+1];
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/* Stacks for the tasks (stacks[0] is kernel stack) */
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unsigned char stacks[MAX_TASKS+1][STACK_SIZE];
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/* MCBs for IPC messages */
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struct mcb msgs[MAX_MSGS];
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/* Pointer to linked list of free MCBs. */
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struct mcb *free_mcbs;
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/* TID of the current user task */
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tid_t curtask = 0;
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/* Statistics */
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int kernel_sched_cnt = 0;
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int kernel_syscall_cnt = 0;
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/* Timestamp via or1ksim (CPU cycle number). */
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unsigned long timestamp()
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{
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register unsigned long cycles asm("r3");
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asm("l.sys 201");
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return cycles;
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}
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/* Standard function for filling memory with a constant byte. */
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void *memset(void *dst, int c, size_t size)
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{
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char *tmp = dst;
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for(;tmp && (tmp < (char *)dst + size); tmp++)
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*(char *)tmp = (char)c;
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return dst;
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}
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/* Traverse linked list of MCBs and show individual messages. */
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void kernel_show_mcbs(struct mcb *mcb)
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{
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for(;mcb; mcb = mcb->next) {
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printf("MCB len=%u origintask=%u ", mcb->length, mcb->origin);
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printf("msg:%s\n", mcb->msg);
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}
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}
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/* Show all contexts. */
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void kernel_show_contexts()
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{
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int i;
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tid_t t;
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for(t = 1; t <= MAX_TASKS; t++) {
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printf("\ntask TID=%d: PC=0x%x ", t, (unsigned)tasks[t].regs.pc & ~0x3);
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printf("SP(r1)=0x%x ", (unsigned)tasks[t].regs.sp);
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printf("SR[IEE]=%d\n", (unsigned)tasks[t].regs.sr & SPR_SR_IEE);
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printf("SR[TEE]=%d\n", (unsigned)tasks[t].regs.sr & SPR_SR_TEE);
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printf("SR[SM]=%d\n", (unsigned)tasks[t].regs.sr & SPR_SR_SM);
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for(i = 1; i < GPRS; i++) {
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if (i % 4 == 0)
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printf("\n");
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printf("r%d=0x%.8x ", i, (unsigned)tasks[t].regs.gprs[i]);
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}
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printf("\n");
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kernel_show_mcbs(tasks[t].waiting_msgs);
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}
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printf("\n");
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}
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/* Simple round-robin scheduler that directly calls dispatcher. It is
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called by low level external interrupt exception handler or by
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kernel_syscall if KERNEL_SYSCALL_SCHED is defined. */
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void kernel_sched()
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{
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if ((++curtask > MAX_TASKS) || !(tasks[curtask].regs.pc & ~0x3))
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curtask = 1;
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task_context = (unsigned long *)&tasks[curtask].regs;
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#if KERNEL_OUTPUT
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printf("kernel_sched(): entry number %d, ", ++kernel_sched_cnt);
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printf("dispatching task TID=%d, time %u cycles", curtask, timestamp());
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kernel_show_contexts();
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#endif
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dispatch();
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}
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/* System call uos_msgsnd. */
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void
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uos_msgsnd(tid_t desttask, char *buf, int len)
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{
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asm("l.sys 1");
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asm("l.nop");
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}
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/* System call uos_msgrcv. */
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void
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uos_msgrcv(tid_t origintask, char *buf, int len)
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{
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asm("l.sys 2");
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asm("l.nop");
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}
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/* Handles system call uos_msgsnd. */
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void kernel_msgsnd(tid_t tid)
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{
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struct mcb *mcb;
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struct mcb **dstmq;
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struct tcb *task;
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task = &tasks[tid];
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/* Sanity checks. */
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/* Does destination task exist? */
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if (!task->regs.gprs[1] || (task->regs.gprs[1] > MAX_TASKS)) {
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task->regs.gprs[9] = IPC_ENOTASK;
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return;
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}
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/* Are there any free MCBs? */
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if (!free_mcbs) {
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task->regs.gprs[9] = IPC_EOUTOFMCBS;
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return;
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}
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/* Is message too big to fit into MCB's message buffer? */
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if (task->regs.gprs[3] > MAX_MSGLEN) {
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task->regs.gprs[9] = IPC_ETOOBIG;
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return;
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}
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/* OK, send the message. */
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/* First, allocate MCB. */
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mcb = free_mcbs;
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free_mcbs = mcb->next;
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/* Second, copy message to the MCB. */
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memcpy(mcb->msg, (void *)task->regs.gprs[2], task->regs.gprs[3]);
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mcb->origin = tid;
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mcb->length = task->regs.gprs[3];
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mcb->next = NULL;
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/* Insert MCB into destination task's message queue at
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the end. */
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dstmq = &tasks[task->regs.gprs[1]].waiting_msgs;
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for(;*dstmq;)
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dstmq = &((*dstmq)->next);
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*dstmq = mcb;
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task->regs.gprs[9] = IPC_NOERR;
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return;
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}
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/* Handles system call uos_msgrcv. */
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void kernel_msgrcv(tid_t tid)
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{
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struct mcb *curmsg, **linkp;
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struct tcb *task;
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task = &tasks[tid];
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/* Sanity checks. */
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/* Does origin task exist? */
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if (task->regs.gprs[1] > MAX_TASKS) {
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task->regs.gprs[9] = IPC_ENOTASK;
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return;
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}
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/* Are there any messages waiting for reception? */
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if (!task->waiting_msgs) {
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task->regs.gprs[9] = IPC_ENOMSGS;
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return;
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}
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/* OK, receive the message. */
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/* Search waiting messages for one coming from origintask. If
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origintask is zero then grab the first message. */
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curmsg = task->waiting_msgs;
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linkp = &task->waiting_msgs;
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for(;task->regs.gprs[1] && curmsg->next && curmsg->origin != task->regs.gprs[1];) {
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linkp = &curmsg->next;
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curmsg = curmsg->next;
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}
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/* Is receive buffer too small for receiving message? */
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if (task->regs.gprs[3] < curmsg->length) {
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task->regs.gprs[9] = IPC_ETOOBIG;
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return;
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}
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/* Now copy the message from the MCB. */
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memcpy((void *)task->regs.gprs[2], curmsg->msg, task->regs.gprs[3]);
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/* Remove MCB from task's waiting queue and place it
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back into free MCBs queue. */
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*linkp = curmsg->next;
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curmsg->next = free_mcbs;
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free_mcbs = curmsg;
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task->regs.gprs[9] = IPC_NOERR;
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return;
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}
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/* Handles all uOS system calls. It is called by low level system call
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exception handler. */
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void kernel_syscall()
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{
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unsigned short syscall_num;
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#if KERNEL_OUTPUT
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printf("kernel_syscall(): entry number %d, ", ++kernel_syscall_cnt);
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printf("current TID=%d, time %u cycles", curtask, timestamp());
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kernel_show_contexts();
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#endif
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syscall_num = *(unsigned short *)((tasks[curtask].regs.pc & ~0x3) - 6);
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switch(syscall_num) {
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case IPC_MSGSND:
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kernel_msgsnd(curtask);
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break;
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case IPC_MSGRCV:
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kernel_msgrcv(curtask);
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break;
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default:
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printf("kernel_syscall(): unknown syscall (%u)\n", syscall_num);
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}
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#if KERNEL_SYSCALL_SCHED
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kernel_sched();
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#endif
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dispatch();
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}
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/* Called by reset exception handler to initialize the kernel and start
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rolling first task. */
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void
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kernel_init()
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{
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tid_t t;
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int i;
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printf("Initializing kernel:\n");
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printf(" Clearing kernel structures...\n");
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memset(tasks, 0, sizeof(tasks));
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memset(stacks, 0, sizeof(stacks));
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memset(msgs, 0, sizeof(msgs));
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printf(" Initializing MCBs... %d MCB(s)\n", MAX_MSGS);
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for(i = 0; i < (MAX_MSGS - 1); i++)
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msgs[i].next = &msgs[i+1];
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free_mcbs = &msgs[0];
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printf(" Initializing TCBs... %d user task(s)\n", MAX_TASKS);
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tasks_entries();
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for(t = 0; t <= MAX_TASKS; t++) {
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tasks[t].regs.sp = (unsigned long)stacks[t] + STACK_SIZE - 4;
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/* Disable EXR for kernel context */
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tasks[t].regs.sr |= (t == 0 ? SPR_SR_SM : SPR_SR_TEE | SPR_SR_IEE);
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tasks[t].regs.gprs[1] = t;
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}
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/* First task runs in seprvisor mode */
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tasks[1].regs.sr |= SPR_SR_SM;
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/* TID=0 is reserved for kernel use */
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kernel_context = (unsigned long *)&tasks[0].regs;
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/* First task to be scheduled is task TID=1 */
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task_context = (unsigned long *)&tasks[1].regs;
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/* Initialize initrrupt controller */
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int_init();
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printf(" Exceptions will be enabled when first task is dispatched.\n");
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printf("Kernel initalized. Starting first user task.\n");
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#if KERNEL_SYSCALL_SCHED
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kernel_sched(); /* Lets schedule and dispatch our first task */
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#else
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tick_init(TICK_PERIOD, kernel_sched);
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kernel_sched(); /* Lets schedule and dispatch our first task */
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#endif
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/* ... */ /* We never get here */
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}
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int main ()
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{
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kernel_init();
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return 0;
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}
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