4 * This file is part of BeRTOS.
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18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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29 * Copyright 2007, 2008 Develer S.r.l. (http://www.develer.com/)
33 * \brief ARM context switch
36 * \author Stefano Fedrigo <aleph@develer.com>
37 * \author Francesco Sacchi <batt@develer.com>
38 * \author Andrea Righi <arighi@develer.com>
41 #include "cfg/cfg_proc.h"
43 /* void asm_switch_context(void **new_sp [r0], void **save_sp [r1]) */
44 .globl asm_switch_context
47 stmfd sp!, {r4 - r11, lr}
48 /* Save old stack pointer */
50 /* Load new stack pointer */
52 /* Load new registers */
53 ldmfd sp!, {r4 - r11, pc}
55 #if CONFIG_KERN_PREEMPT
57 /* ARM interrupt mode with IRQ and FIQ disabled */
58 #define ARM_IRQ_MODE 0xD2
59 /* ARM supervisor mode with IRQ and FIQ disabled */
60 #define ARM_SVC_MODE 0xD3
62 .globl asm_irq_switch_context
63 asm_irq_switch_context:
64 /* Return if preemption is not needed */
67 ldmeqfd sp!, {r0 - r3, ip, pc}^
69 /* Otherwise restore regs used by the ISR */
70 ldmfd sp!, {r0 - r3, ip, lr}
72 /* Save current process context */
73 msr cpsr_c, #ARM_SVC_MODE
74 stmfd sp!, {r0 - r3, ip, lr}
76 /* Save lr_irq and spsr_irq in process stack */
77 msr cpsr_c, #ARM_IRQ_MODE
80 msr cpsr_c, #ARM_SVC_MODE
83 /* Perform the context switch */
86 /* Restore lr_irq and spsr_irq from process stack */
88 msr cpsr_c, #ARM_IRQ_MODE
92 /* Restore process regs */
93 msr cpsr_c, #ARM_SVC_MODE
94 ldmfd sp!, {r0 - r3, ip, lr}
97 msr cpsr_c, #ARM_IRQ_MODE
99 #endif /* CONFIG_KERN_PREEMPT */