WinCE中划分Storage Memory和Program Memory

The RAM on a Windows CE–based device is divided into two areas: the object store and the program memory.

The object store resembles a permanent, virtual RAM disk. Data inthe object store is retained when you suspend or perform a soft resetoperation on the system. Devices typically have a backup power supplyfor the RAM to preserve data if the main power supply is interruptedtemporarily. When operation resumes, the system looks for a previouslycreated object store in RAM and uses it, if one is found. Devices thatdo not have battery-backed RAM can use the hive-based registry topreserve data during multiple boot processes.

The program memory consists of the remaining RAM. Program memoryworks like the RAM in personal computers — it stores the heaps andstacks for the applications that are running.

我承认我很懒，上面一段话的URL是ms-help://MS.WindowsCE.500/wcecoreos5/html/wce50conMemoryArchitecture.htm

具体的设置可以在系统启动后，Control Panel -> System -> Memory里面看到。默认的是把内存五五开，一半给Storage Memory， 一半给ProgramMemory用。这样显然是不合算的。以64M的RAM为例, 启动后Storage Memory 32M,而因为没有留出界面让用户往里面拷东西, 任何时候in use都不会超过10M; Program Memory也是32M,但启动后就用掉27M, 实际上应用程序可用的内存只有5M, 一旦达到了上限,那么每前进一步都要很艰难地去释放几十K内存，然后用掉，再去释放几十K内存，如此循环，此时应用程序的运行速度狂慢无比.

划分的方法也很简单, 只不过可能没人注意到而已.

说明在ms-help://MS.WindowsCE.500/wceosdev5/html/wce50lrfFSRAMPERCENT.htm  懒得看英文的人就继续往下看

其实说白了就一句话, 在BSP的config.bib里 CONFIG 区添加这个变量 FSRAMPERCENT = 0xXXXXXX, 但注意两点，

(1) 必须写在config.bib的CONFIG区里, 不是plagform.bib不是config.reg等其他文件而是config.bib，也不是config.bib文件的任意地方而一定要在CONFIG REGION里.
(2) FSRAMPERCENT这个变量一定得写为FSRAMPERCENT, 不能写成FSROMPERCENT不能写成ILOVEU, 或者阿猫阿狗什么的.

写下这两句的时候本人已经打开无敌光环, 免疫一切鸡蛋和西红柿.

FSRAMPERCENT是一个4byte长度的十六进制数, 我们用代数假设 FSRAMPERCENT = 0xQXYZ, 其中Q,X,Y,Z都是十六进制数

那么最终划分给Storage Memory的大小 =  ( Q + X + Y +  Z ) / 0x400 * TOTAL_RAM_SIZE

以文中的例子来算, FSRAMPERCENT=0x10203040, 假设TOTAL_RAM_SIZE=64M, 那么StorageMemory= (0x10 + 0x20 + 0x30 + 0x40) / 0x400 * 64M = 10M.

顺路鄙视一下，WinXP自带的计算器里无法输入和计算带小数位的非十进制数.