diff options
Diffstat (limited to 'nuttx/arch/arm/src/armv6-m/up_saveusercontext.S')
| -rw-r--r-- | nuttx/arch/arm/src/armv6-m/up_saveusercontext.S | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/armv6-m/up_saveusercontext.S b/nuttx/arch/arm/src/armv6-m/up_saveusercontext.S new file mode 100644 index 000000000..7bc14e4c4 --- /dev/null +++ b/nuttx/arch/arm/src/armv6-m/up_saveusercontext.S @@ -0,0 +1,106 @@ +/************************************************************************************ + * arch/arm/src/armv6-m/up_saveusercontext.S + * + * Copyright (C) 2013 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ************************************************************************************/ + +/************************************************************************************ + * Included Files + ************************************************************************************/ + +#include <nuttx/config.h> +#include <arch/irq.h> + +#include "nvic.h" +#include "svcall.h" + +/************************************************************************************ + * Pre-processor Definitions + ************************************************************************************/ + +/************************************************************************************ + * Global Symbols + ************************************************************************************/ + + .cpu cortex-m0 + .file "up_saveusercontext.S" + +/************************************************************************************ + * Macros + ************************************************************************************/ + +/************************************************************************************ + * Public Functions + ************************************************************************************/ + +/************************************************************************************ + * Name: up_saveusercontext + * + * Description: + * Save the current thread context. Full prototype is: + * + * int up_saveusercontext(uint32_t *saveregs); + * + * Return: + * 0: Normal return + * 1: Context switch return + * + ************************************************************************************/ + + .text + .align 2 + .code 16 + .thumb_func + .globl up_saveusercontext + .type up_saveusercontext, function +up_saveusercontext: + + /* Perform the System call with R0=0 and R1=regs */ + + mov r1, r0 /* R1: regs */ + mov r0, #SYS_save_context /* R0: save context (also return value) */ + svc 0 /* Force synchronous SVCall (or Hard Fault) */ + + /* There are two return conditions. On the first return, R0 (the + * return value will be zero. On the second return we need to + * force R0 to be 1. + */ + + mov r3, #(4*REG_R0) /* R3=Offset to R0 storage */ + add r2, r1, r3 /* R2=Address of R0 storage */ + mov r3, #1 /* R3=Return value of one */ + str r3, [r2, #0] /* Save return value */ + bx lr /* "normal" return with r0=0 or + * context switch with r0=1 */ + .size up_saveusercontext, .-up_saveusercontext + .end + |