zyfeier commented on code in PR #9019: URL: https://github.com/apache/nuttx/pull/9019#discussion_r1172299455
########## arch/arm/src/armv6-m/arm_saveusercontext.S: ########## @@ -0,0 +1,108 @@ +/**************************************************************************** + * arch/arm/src/armv6-m/arm_saveusercontext.S + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> +#include <nuttx/irq.h> + + .file "arm_saveusercontext.S" + + .text + .syntax unified + .thumb + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: up_saveusercontext + * + * Description: + * Save the current context. Full prototype is: + * + * int up_saveusercontext(void *saveregs); + * + * R0 = saveregs = pinter saved array + * + * Returned Value: + * None + * + ****************************************************************************/ + + .globl up_saveusercontext + .globl up_saveusercontext + .type up_saveusercontext, %function + +up_saveusercontext: + + /* Save r0~r3 */ + + str r0, [r0, #(4*REG_R0)] Review Comment: Although r0~r3 are contiguous, if we need to use the stmia instruction, we need to first set a register to r0+4*SW_XCPT_REGS, and then use the stmia instruction, and also need one register to save the old r0. This does not save instructions, but instead increases the number of instructions. Therefore, it is more appropriate to use the str instruction directly. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@nuttx.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
