开发环境
- wsl1 ubuntu 20.04
- gcc-arm-none-eabi-9-2019-q4-major
- N32G452REL7开发板(rt-thread nano)
C++端配置和打包
文件夹结构
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9my_math
├── build
│ ├── libmy_math.a
│ └── my_math.o
├── include
│ └── my_math.h
├── Makefile
└── src
└── my_math.cppmy_math.h1
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extern "C" {
/**
* @brief 对输入数组执行处理并返回浮点结果
* @param data 输入数组
* @param len 数组长度
* @return 浮点结果
*/
float my_process(const float* data, int len);
}my_math.cpp1
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/**
* 思想：输入数组 -> 拷贝到动态buffer -> 处理 -> 输出平均值(示例)
*/
float my_process(const float* data, int len) {
if (data == nullptr || len <= 0) {
return 0.0f;
}
// 动态容器（内部malloc）
std::vector<float> buf;
buf.reserve(len);
// 拷贝
for (int i = 0; i < len; i++) {
buf.push_back(data[i]);
}
// 浮点运算示例：计算均方根
float sum = 0.0f;
for (int i = 0; i < len; i++) {
sum += buf[i] * buf[i];
}
float rms = std::sqrt(sum / (float)len);
return rms;
}Makefile文件，关键配置：-mfpu=fpv4-sp-d16-mfloat-abi=hard-std=c++111
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50# ======= 编译器选项 =======
CC = arm-none-eabi-g++
AR = arm-none-eabi-ar
# ======= FPU & 优化 =======
CFLAGS = -mcpu=cortex-m4 \
-mthumb \
-mfloat-abi=hard \
-mfpu=fpv4-sp-d16 \
-Os \
-ffunction-sections \
-fdata-sections \
-std=c++11 \
-Wall
INCLUDE = -Iinclude
# ======= 路径定义 =======
SRC_DIR = src
BUILD_DIR = build
# ======= 自动扫描所有源文件 =======
SOURCES := $(wildcard $(SRC_DIR)/*.cpp)
# ======= 自动生成对应对象文件名 =======
OBJECTS := $(patsubst $(SRC_DIR)/%.cpp,$(BUILD_DIR)/%.o,$(SOURCES))
# ======= 输出静态库 =======
LIB = $(BUILD_DIR)/libmy_math.a
# ======= 默认目标 =======
all: $(LIB)
# ======= 创建静态库 =======
$(LIB): $(OBJECTS)
$(AR) rcs $@ $^
# ======= 编译 .cpp 到 .o =======
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp | $(BUILD_DIR)
$(CC) $(CFLAGS) $(INCLUDE) -c $< -o $@
# ======= 创建 build 目录 =======
$(BUILD_DIR):
mkdir -p $(BUILD_DIR)
# ======= 清理 =======
clean:
rm -rf $(BUILD_DIR)
MCU端配置和打包
添加文件夹
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3lib
├── libmy_math.a
└── my_math.hMakefile中添加1
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17# mcu中添加配置
MCU = -mcpu=cortex-m4 -mthumb \
-mfpu=fpv4-sp-d16 -mfloat-abi=hard \ # 增加硬浮点编译
-ffunction-sections \
-fdata-sections \
--specs=nosys.specs \
-Os -ggdb
# 头文件路径加上lib
INCLUDE += -Ilib
# 最后链接添加lib
TARGET_LIBS += -Llib -lmy_math -lstdc++ -lsupc++ -lm # 找到 libmy_math.a, C++ runtime lib, math lib
# 增加链接规则
$(TARGET).elf: $(OBJECTS)
$(CC) $(ASM_OBJECTS) $(C_OBJECTS) $(LDFLAGS) $(TARGET_LIBS) -Wl,-Map=$(TARGET).map -o $(TARGET).elfrt-thread nano需要修改context_gcc.S1
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27#if defined (__VFP_FP__) && !defined(__SOFTFP__)
TST lr, #0x10 /* if(!EXC_RETURN[4]) */
IT EQ /* 新增适配硬浮点适配：下面一条指令仅在 Z=1 时执行 */
VSTMDBEQ r1!, {d8 - d15} /* push FPU register s16~s31 */
#endif
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
MOV r4, #0x00 /* flag = 0 */
TST lr, #0x10 /* if(!EXC_RETURN[4]) */
IT EQ /* 新增适配硬浮点适配：下面一条指令仅在 Z=1 时执行 */
MOVEQ r4, #0x01 /* flag = 1 */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
CMP r3, #0 /* if(flag_r3 != 0) */
IT NE /* 新增适配硬浮点，下一条指令在 Z=0（比较结果不相等）时执行。 */
VLDMIANE r1!, {d8 - d15} /* pop FPU register s16~s31 */
#endif
MSR psp, r1 /* update stack pointer */
#if defined (__VFP_FP__) && !defined(__SOFTFP__)
ORR lr, lr, #0x10 /* lr |= (1 << 4), clean FPCA. */
CMP r3, #0 /* if(flag_r3 != 0) */
IT NE /* 新增适配硬浮点，下一条指令在 Z=0（比较结果不相等）时执行。 */
BICNE lr, lr, #0x10 /* lr &= ~(1 << 4), set FPCA. */
#endif
使用例程
- 使用例程及堆栈
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// 打印rtthread heap的数据信息
static void print_heap(const char* tag)
{
rt_uint32_t total = 0, used = 0, max_used = 0;
rt_memory_info(&total, &used, &max_used);
rt_uint32_t free = total - used;
logDebug("[%s] heap total=%u used=%u free=%u max_used=%u",
tag, total, used, free, max_used);
}
extern char end; // 链接器脚本定义的 end，heap 起点
extern char _estack; // 链接器脚本定义的 stack 顶
// 打印标准heap的数据信息
void print_libc_heap(void)
{
void* heap_end = _sbrk(0); // 当前 heap top
size_t used = (char*)heap_end - &end; // 已用 heap
size_t free = &_estack - (char*)heap_end; // 剩余给 heap 的空间（理论上）
logDebug("libc heap used=%u, free=%u, heap_start=%p, heap_end=%p, stack_top=%p",
(unsigned int)used, (unsigned int)free, &end, heap_end, &_estack);
}
void my_test_cpp(int array0)
{
float arr[1024] = {1,2,3,4,5};
arr[0] = (float)array0;
print_heap("before my_process");
print_libc_heap();
float out = my_process(arr, sizeof(arr)/sizeof(arr[0]));
print_heap("after my_process");
print_libc_heap();
logDebug("my_test_cpp out = [%f]", out);
}
SHELL_EXPORT_CMD(SHELL_CMD_PERMISSION(0)|SHELL_CMD_TYPE(SHELL_TYPE_CMD_FUNC)|SHELL_CMD_DISABLE_RETURN, my_test_cpp, my_test_cpp, my_test_cpp 1 or 0);
void my_rt_heap_test(void)
{
for (int i = 0; i < 10; i++)
{
int size = 128 * (i + 1);
print_heap("before my_process");
void *p = rt_malloc(size);
if (p)
{
logDebug("my_heap_test malloc size = [%d] success, addr = [%p]", size, p);
rt_memset(p, 0xA5, size);
rt_free(p);
print_heap("before my_process");
logDebug("my_heap_test free addr = [%p]", p);
}
else
{
logError("my_heap_test malloc size = [%d] failed!", size);
}
print_heap("after my_process");
}
}
SHELL_EXPORT_CMD(SHELL_CMD_PERMISSION(0)|SHELL_CMD_TYPE(SHELL_TYPE_CMD_FUNC)|SHELL_CMD_DISABLE_RETURN, rt_heap_test, my_rt_heap_test, my_rt_heap_test);
void my_heap_test(void)
{
for (int i = 0; i < 10; i++)
{
int size = 128 * (i + 1);
print_libc_heap();
void *p = malloc(size);
if (p)
{
logDebug("my_heap_test malloc size = [%d] success, addr = [%p]", size, p);
memset(p, 0xA5, size);
free(p);
print_libc_heap();
logDebug("my_heap_test free addr = [%p]", p);
}
else
{
logError("my_heap_test malloc size = [%d] failed!", size);
}
print_heap("after my_process");
}
}
SHELL_EXPORT_CMD(SHELL_CMD_PERMISSION(0)|SHELL_CMD_TYPE(SHELL_TYPE_CMD_FUNC)|SHELL_CMD_DISABLE_RETURN, heap_test, my_heap_test, my_heap_test);