Add ARM task switching support\!

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@916 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/cpu/cpu.h b/cpu/cpu.h
index af769d644293c3e5f37221328c2a5acc655df6b1..cf79f7efd4483fbc8c8b1c11ea4f843812a3adad 100644 (file)
--- a/cpu/cpu.h
+++ b/cpu/cpu.h
@@ -120,7 +120,7 @@
        /* Register counts include SREG too */
        #define CPU_REG_BITS           32
        #define CPU_REGS_CNT           16
-       #define CPU_SAVED_REGS_CNT     FIXME
+       #define CPU_SAVED_REGS_CNT     9
        #define CPU_STACK_GROWS_UPWARD 0
        #define CPU_SP_ON_EMPTY_SLOT   0
        #define CPU_BYTE_ORDER         (__BIG_ENDIAN__ ? CPU_BIG_ENDIAN : CPU_LITTLE_ENDIAN)
@@ -203,7 +203,7 @@
                        ); \
                } while (0)
 
-               #define IRQ_GETSTATE() \
+               #define CPU_READ_FLAGS() \
                ({ \
                        uint32_t sreg; \
                        asm volatile ( \
@@ -211,9 +211,20 @@
                                : "=r" (sreg) \
                                : /* no inputs */ \
                        ); \
-                       !((sreg & 0xc0) == 0xc0); \
+                       sreg; \
                })
 
+               #define IRQ_GETSTATE() (!((CPU_READ_FLAGS() & 0xc0) == 0xc0))
+
+               /**
+                * Initialization value for registers in stack frame.
+                * The register index is not directly corrispondent to CPU
+                * register numbers, but is related to how are pushed to stack (\see asm_switch_context).
+                * Index (CPU_SAVED_REGS_CNT - 1) is the CPSR register:
+                * the initial value is taken from current CPSR.
+                */
+               #define CPU_REG_INIT_VALUE(reg) (reg == (CPU_SAVED_REGS_CNT - 1) ? CPU_READ_FLAGS() : 0)
+
        #endif /* !__IAR_SYSTEMS_ICC_ */
 
 #elif CPU_PPC

diff --git a/kern/switch_arm.S b/kern/switch_arm.S
new file mode 100644 (file)
index 0000000..808b712
--- /dev/null
+++ b/kern/switch_arm.S
@@ -0,0 +1,68 @@
+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2001,2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999,2000,2001 Bernardo Innocenti <bernie@develer.com>
+ *
+ * -->
+ *
+ * \brief ARM context switch
+ *
+ * \version $Id: proc.c 18271 2007-10-11 14:51:31Z batt $
+ *
+ * \author Stefano Fedrigo <aleph@develer.com>
+ * \author Francesco Sacchi <batt@develer.com>
+ */
+
+
+/*
+ * NOTE: At each change of this function affecting proc.c
+ * (i.e. arguments, data stored in the stack) bump up version
+ * number in asm_switch_version().
+ */
+
+/* void asm_switch_context(void **new_sp, void **save_sp) */
+.globl asm_switch_context
+asm_switch_context:
+       mrs     r2, cpsr               /* Save status. */
+       stmfd   sp!, {r2, r4-r11, lr}  /* Save registers. */
+
+       str     sp, [r1]               /* Save old stack pointer. */
+       ldr     sp, [r0]               /* Load new stack pointer */
+
+       ldmfd   sp!, {r2, r4-r11, lr}  /* Load new registers. */
+       msr     cpsr, r2               /* restore flags reg. */
+
+       mov     pc, lr
+
+
+/* int asm_switch_version(void) */
+.globl asm_switch_version
+asm_switch_version:
+       mov     r0, #1
+       mov     pc, lr