start_addr=0x30000000 end_addr=0x30000003 data_write=0x55AA55AA count=0 match_count=0 # 写入数据 for ((addr=$start_addr; addr<$end_addr+1; addr=addr+4)); do echo -ne "\x55\xAA\x55\xAA" | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/null data=$(echo -ne "\x55\xAA\x55\xAA" | hexdump -e '/4 "%08x\n"') data_read=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') if [ "$data_read" == "$data" ]; then match_count=$((match_count+1)) fi count=$((count+1)) done # 输出结果 echo "data: $data" echo "data_read: $data_read" echo "match_count: $match_count" echo "count: $count" # 判断结果 if [ $match_count -eq $count ]; then echo "PASS" else echo "FAIL" fi这段代码为什么match_count和count输出的是1,我的设想是从起始地址到终止地址一共四个地址,不应该是比较4次吗?请注意我想比较的是data_read和data,请在满足我想比较的数据的前提下完成count数值等于从起始地址到终止地址这一要求。我是想要每个地址写入1个数据,写入完成后在下一个地址写入,每次写入地址后读取然后比较,比较完成后match_count与count计数改变,从起始地址开始到终止地址写入结束后输出match_count和count,因此按照我的代码的起始地址和终止地址不应该是比较四次吗?
时间: 2024-04-28 09:20:10 浏览: 25
在这段代码中,每次写入数据时,使用的偏移量是 $addr/8,而每次读取数据时使用的偏移量是 $addr/4。这是因为在写入数据时,使用的是 dd 命令,其中的 bs 参数是 4,而 dd 命令会将 bs 参数指定的字节数转换为块数,因此 bs=4 时,每块大小为 4 字节,这也就是为什么偏移量要除以 8。而在读取数据时,使用的是 dd 命令,其中的 bs 参数也是 4,因此每块大小为 4 字节,这也就是为什么偏移量要除以 4。
因此,这段代码实际上只写入和比较了一个 4 字节的数据,而不是写入和比较了四个 4 字节的数据。如果想要每个地址写入一个数据,应该将偏移量修改为 $addr,并且将 bs 参数修改为 1。这样,每次写入和读取的大小就是 1 字节,每个地址都会写入一个数据,也会进行四次比较。
相关问题
start_addr=0x30000000 end_addr=0x30000003 data_write=0x55AA55AA count=0 match_count=0 # 写入数据 for ((addr=$start_addr; addr<$end_addr+1; addr=addr+1)); do echo -ne "\x55\xAA\x55\xAA" | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/null data=$(echo -ne "\x55\xAA\x55\xAA" | hexdump -e '/4 "%08x\n"') echo "data: $data" data_read=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') echo "data_read: $data_read" if [ "$data_read" == "$data" ]; then match_count=$((match_count+1)) echo "match_count: $match_count" fi count=$((count+1)) echo "count: $count" done # 输出结果 # 判断结果 if [ $match_count -eq $count ]; then echo "PASS" else echo "FAIL" fi 为什么这段代码data和data_read输出的都是空白?
这段代码中,数据写入和读取操作都使用了`dd`命令和`hexdump`命令。但是,`dd`命令和`hexdump`命令都是用于二进制数据的传输和显示,而不是文本数据。因此,如果想要在终端中查看二进制数据,需要使用`xxd`命令或者`od`命令。所以,将`hexdump`命令替换成`xxd`命令或者`od`命令即可输出正确的数据。
修改后的代码如下:
```
start_addr=0x30000000 end_addr=0x30000003 data_write=0x55AA55AA count=0 match_count=0
# 写入数据
for ((addr=$start_addr; addr<$end_addr+1; addr=addr+1)); do
echo -ne "\x55\xAA\x55\xAA" | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/null
data=$(echo -ne "\x55\xAA\x55\xAA" | xxd -p)
echo "data: $data"
data_read=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | xxd -p)
echo "data_read: $data_read"
if [ "$data_read" == "$data" ]; then
match_count=$((match_count+1))
echo "match_count: $match_count"
fi
count=$((count+1))
echo "count: $count"
done
# 判断结果
if [ $match_count -eq $count ]; then
echo "PASS"
else
echo "FAIL"
fi
```
start_addr=0x05877000 #end_addr=0x3ffff000 end_addr=0x05877002 data_write=0x55AA55AA data_read=$(printf "%08x" $data_write) count=0 match_count=0 for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul done for ((addr=$start_addr; addr<$end_addr; addr+=4)); do data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') if [ "$data_read" == "$data" ]; then match_count=$((match_count+1)) fi count=$((count+1)) done echo $data echo $data_read那么该如何修改程序才能让程序输出PASS
为了让程序输出 PASS,我们需要在循环结束后,判断 match_count 是否等于 count,如果等于,即所有数据都成功读取并且与写入的数据一致,就输出 PASS。
修改后的代码如下:
```
start_addr=0x05877000
end_addr=0x3ffff000
data_write=0x55AA55AA
data_read=$(printf "%08x" $data_write)
count=0
match_count=0
for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do
echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul
done
for ((addr=$start_addr; addr<$end_addr; addr+=4)); do
data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"')
if [ "$data_read" == "$data" ]; then
match_count=$((match_count+1))
fi
count=$((count+1))
done
if [ $match_count -eq $count ]; then
echo "PASS"
else
echo "FAIL"
fi
echo $data
echo $data_read
```
这样,当所有数据都成功读取并且与写入的数据一致时,程序就会输出 PASS。
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