nuttx/arch/arm/src/armv7-a/arm_fpucmp.c
zhangyuan21 ffd2eb5b14 arch/arm: only compare callee-saved registers for fpu
Registers S0-S15 (D0-D7, Q0-Q3) do not need to be preserved. They can be used for passing
arguments or returning results in standard procedure-call variants.
Registers D16-D31 (Q8-Q15), do not need to be preserved.

Signed-off-by: zhangyuan21 <zhangyuan21@xiaomi.com>
2022-12-09 11:00:38 +08:00

72 lines
2.5 KiB
C

/****************************************************************************
* arch/arm/src/armv7-a/arm_fpucmp.c
*
* 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 <stdint.h>
#include <string.h>
#include <nuttx/irq.h>
#include "arm_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifdef CONFIG_ARCH_FPU
# define FPU_CALLEE_REGS (16)
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_fpucmp
*
* Description:
* Compare FPU areas from thread context.
*
* Input Parameters:
* saveregs1 - Pointer to the saved FPU registers.
* saveregs2 - Pointer to the saved FPU registers.
*
* Returned Value:
* True if FPU areas compare equal, False otherwise.
*
****************************************************************************/
bool up_fpucmp(const void *saveregs1, const void *saveregs2)
{
const uint32_t *regs1 = saveregs1;
const uint32_t *regs2 = saveregs2;
/* Only compare callee-saved registers, caller-saved registers do not
* need to be preserved.
*/
return memcmp(&regs1[REG_S16], &regs2[REG_S16], 4 * FPU_CALLEE_REGS) == 0;
}
#endif /* CONFIG_ARCH_FPU */