关于MDK中:RO-data、RW-data、ZI-data

最近在LPC2109上调试ENC28J60，协议栈使用的是UIP，刚开始用的telnet服务，能够正常编译运行。然后换成webserver提示：

enc28j60.axf: Error: L6406E: No space in execution regions with .ANY selector matching uip.o(.bss).

enc28j60.axf: Error: L6407E: Sections of aggregate size 0x2204 bytes could not fit into .ANY selector(s).

很是奇怪，然后把芯片换成大一点的发现ZI-data增加了很多。

然后看了网上查了下关于ZI-DATA的信息，又看了MDK的手册,下面是手册对于这几个数据的解释：

RO Data

Shows how many bytes are occupied by read-only data. This is in addition to the inline data included in the Code (inc. data) column.
RW Data

Shows how many bytes are occupied by read-write data.
ZI Data

Shows how many bytes are occupied by zero-initialized data.

以及他们的存储信息：

Example . Image component size informatioCode (inc. data) RO Data RW Data ZI Data De
                                        Object Totals
                                                      (incl. Generated)
                                                       (incl. Padding)
                                         Library Totals
                                                       (incl. Padding)

===============================================================================

Code (inc. data)   RO Data    RW Data    ZI Data      Debug
                                      Grand Totals
                                      ELF Image Totals
                                              ROM Totals

===============================================================================

Total RO  Size (Code + RO Data)              (  .30kB)
Total RW  Size (RW Data + ZI Data)           (  .30kB)
Total ROM Size (Code + RO Data + RW Data)    (  .35kB)

看了网上的篇文章，大概是讲对这些数据的存储的测试验证。
然后自己动手在MDK下测试了下，发现数据很奇怪。

#include <stdio.h>
char ix[];
int main(void)
{
    printf("%c",ix[]);
    return ;
}

刚开始用ix[10]->ix[20]->ix[30]测试，发现结果很奇怪。
通过对初始化为0的变量的增加：发现ZI-data是以8为单位增加的。
不解，以前的实验室的师兄告诉我可能是ARM的数据存储是以字为单位，觉得有道理，尝试，定义数组ix[8]->...->ix[12]->ix[16]->ix[20]->ix[24]->ix[25]逐个增加编译

Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
...........
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=
Program Size: Code= RO-data= RW-data= ZI-data=  

MDK的ZI-data是以8bytes为单位增加。