什么是gel文件？gel文件能干什么？
gel全称General Extended Language，即通用扩展语言文件，gel文件中由类似C语言的代码构成，gel语言是一种解释性语言，gel文件扩展名为.gel；
gel文件用于（1）扩展CCS功能，比如菜单选项等，（2）通过gel可以访问目标板的存储器。
1. gel基本语法——类C
gel函数和gel参数不需要在DSP程序中定义。gel具有C语言的很多相似的东西：函数、return语句、if-else语句、while语句、与C一样的注释方式、#define，这些函数或语句的用法也与C中的非常类似。
GEL函数
funcName(param1 "discription" [,param2 "discription", param3 "discription",...])
{
statements;
}
gel函数中不用声明返回类型和参数类型，但函数中可以使用return语句返回；
参数使用“参数+字符串类型的描述”组成，参数不需要定义，可以是以下的任意一种：实际/仿真的DSP目标板的符号值；数字常量（表达式或常值）；字符串常量。
GEL函数调用：通常可以在输入C表达式的任意地方调用GEL函数，也可以在另一个GEL函数中调用GEL函数。GEL函数无法递归调用。
GEL语句
返回语句：
return [expression];
条件语句：
if (exp) statements 1; else statements 2;
循环语句：
while (exp) {
statements;
}
GEL预处理
#define identifier(arguments list) token-expression
GEL注释
// 注释
/* 注释 */
2. gel特有关键字
menuitem/hotmenu
在CCS v4.2中测试，menuitem添加Scripts菜单下的子菜单项，hotmenu添加menuitem定义菜单项的子菜单项，参考本文后面的例子。
这两个关键字声明的函数都不需要参数，比如
menuitem "Addressing Modes";
hotmenu C27x_Mode()
{
AMODE = 0;
OBJMODE = 0;
}
hotmenu C28x_Mode()
{
AMODE = 0;
OBJMODE = 1;
}
hotmenu C2xLP_Mode()
{
AMODE = 1;
OBJMODE = 1;
}
上面代码将产生如下的菜单结构，
Scripts
- Addressing Modes
- C27x_Mode
- C28x_Mode
- C2xLP_MODE
dialog
向menuitem定义的菜单中添加一个入口子菜单，并在点击子菜单时弹出对话框。
menuitem "MyFunc"
dialog InitTarget(StartAddr "Starting Address", EndAddr "Ending Address")
{
statements;
}
dialog RefreshTarget()
{
statements;
}
slider
添加滑动条，每次移动滑动条都用滑动条上的新值重新调用GEL文件，定义格式如下，
slider param_def(minVal, maxVal, increment, pageIncrement, paramName)
{
statements;
}
3. gel文件的例子
/*
* This GEL file (DSP621x_671x.gel) provides example code on how to
* reset the C6x DSP and initialize the External Memory Interface.
*
* You will have to edit settings in emif_init() to your own
* specifications as the example is applicable to the C6711 DSK.
*
* This file is has minimal functionality and is designed to be used
* as a starting point for custom GEL files.
*
* Refer to CCS Help for detailed information on GEL commands.
*
*/
/*
* The StartUp() function is called every time you start Code Composer.
* It should only include functions that do not "touch the hardware" -
* Hardware initialization should be invoked from the OnTargetConnect()
* function or the GEL menu.
*/
StartUp()
{
/* setMemoryMap;
this should be a function to initialize the mem map based
on the particular hardware that is used
*/
}
/*--------------------------------------------------------------*/
/* OnTargetConnect() -- this function is called after a target */
/* connect. */
/*--------------------------------------------------------------*/
OnTargetConnect()
{
/* GEL_Reset is used to deal with the worst case senario of
unknown target state. If for some reason a reset is not
desired upon target connection, GEL_Reset may be removed
and replaced with something "less brutal" like a cache
initialization function
GEL_Reset();
*/
}
OnReset(int nErrorCode){
/* emif_init(); */
}
/*
* OnPreFileLoaded()
* This function is called automatically when the 'Load Program'
* Menu item is selected .....
*/
OnPreFileLoaded()
{
CleanCache();
}
/*
* CleanCache()
* Actually Invalidate L1D, L1P, and L2
*/
CleanCache() {
*(int *)0x01845004 = 1;
}
emif_init()
{
/*---------------------------------------------------------------------------*/
/* EMIF REGISTERS */
/*---------------------------------------------------------------------------*/
#define EMIF_GCTL 0x01800000
#define EMIF_CE1 0x01800004
#define EMIF_CE0 0x01800008
#define EMIF_CE2 0x01800010
#define EMIF_CE3 0x01800014
#define EMIF_SDRAMCTL 0x01800018
#define EMIF_SDRAMTIMING 0x0180001C
#define EMIF_SDRAMEXT 0x01800020
/*---------------------------------------------------------------------------*/
/* EMIF REGISTER VALUES - these should be modified to match TARGET hardware */
/*---------------------------------------------------------------------------*/
*(int *)EMIF_GCTL = 0x00003040;/* EMIF global control register */
*(int *)EMIF_CE1 = 0xFFFFFF23; /* CE1 - 32-bit asynch access after boot*/
*(int *)EMIF_CE0 = 0xFFFFFF30; /* CE0 - SDRAM */
*(int *)EMIF_CE2 = 0xFFFFFF23; /* CE2 - 32-bit asynch on daughterboard */
*(int *)EMIF_CE3 = 0xFFFFFF23; /* CE3 - 32-bit asynch on daughterboard */
*(int *)EMIF_SDRAMCTL = 0x07117000; /* SDRAM control register (100 MHz)*/
*(int *)EMIF_SDRAMTIMING = 0x0000061A; /* SDRAM Timing register */
}
上面的gel来自于CCS v4安装目录下ccsv4emulationgelDSP621x_671x.gel文件，上面不仅使用了#define定义寄存器地址，还使用了类似C中的指针对EMIF（外部存储器接口）进行配置。
/******************************************************************/
/* Code Composer Studio supports five reserved GEL functions that */
/* automatically get executed if they are defined. They are: */
/* */
/* StartUp() - Executed whenever CCS is invoked */
/* OnReset() - Executed after Debug->Reset CPU */
/* OnRestart() - Executed after Debug->Restart */
/* OnPreFileLoaded() - Executed before File->Load Program */
/* OnFileLoaded() - Executed after File->Load Program */
/* */
/******************************************************************/
StartUp()
{
/* Initialize F2812 memory map */
GEL_Reset();
F2812_Memory_Map();
/* Enable_DFT(); */
GEL_TextOut("Gel StartUp Complete.
");
}
OnReset(int nErrorCode)
{
Enable_DFT();
}
/* commented out to avoid execution
OnRestart(int nErrorCode)
{
}
OnPreFileLoaded()
{
}
OnFileLoaded(int nErrorCode, int bSymbolsOnly)
{
}
*/
menuitem "Initialize Memory Map";
/*------------------- F2812 Memory Map, MPNMC=0 --------------------*/
/* */
/* Note: M0M1MAP and VMAP signals tied high on F2812 core */
/* */
/* 0x000000 - 0x0007ff M0/M1 SARAM (Prog and Data) */
/* 0x000800 - 0x000fff Peripheral Frame0 (PF0) (Data only) */
/* 0x002000 - 0x003fff XINTF ZONE 0 (Prog and Data) */
/* 0x004000 - 0x005fff XINTF ZONE 1 (Prog and Data) */
/* 0x006000 - 0x006fff Peripheral Frame1 (PF1) (Data only) */
/* 0x007000 - 0x007fff Peripheral Frame2 (PF2) (Data only) */
/* 0x008000 - 0x009fff L0/L1 SARAM (Prog and Data) */
/* 0x080000 - 0x0fffff XINTF ZONE 2 (Prog and Data) */
/* 0x100000 - 0x17ffff XINTF ZONE 6 (Prog and Data) */
/* 0x3d7800 - 0x3d7fff OTP (Prog and Data) */
/* 0x3d8000 - 0x3f7fff FLASH (Prog and Data) */
/* 0x3f8000 - 0x3f9fff H0 SARAM (Prog and Data) */
/* 0x3fc000 - 0x3fffff XINTF ZONE 7 (MPNMC=1) (Prog and Data) */
/* 0x3ff000 - 0x3fffff BOOT ROM (MPNMC=0) (Prog and Data) */
/*------------------------------------------------------------------*/
hotmenu F2812_Memory_Map()
{
GEL_MapReset();
GEL_MapOn();
/* Program memory maps */
GEL_MapAdd(0x0,0,0x800,1,1); /* M0/M1 SARAM */
GEL_MapAdd(0x2000,0,0x2000,1,1); /* XINTF ZONE 0 */
GEL_MapAdd(0x4000,0,0x2000,1,1); /* XINTF ZONE 1 */
GEL_MapAdd(0x8000,0,0x2000,1,1); /* L0/L1 SARAM */
GEL_MapAdd(0x80000,0,0x80000,1,1); /* XINTF ZONE 2 */
GEL_MapAdd(0x100000,0,0x80000,1,1); /* XINTF ZONE 6 */
GEL_MapAdd(0x3d7800,0,0x800,1,0); /* OTP */
GEL_MapAdd(0x3d8000,0,0x20000,1,0); /* FLASH */
GEL_MapAdd(0x3f8000,0,0x2000,1,1); /* H0 SARAM */
/* Data memory maps */
GEL_MapAdd(0x0,1,0x800,1,1); /* M0/M1 SARAM */
GEL_MapAdd(0x800,1,0x800,1,1); /* PF0 */
GEL_MapAdd(0x2000,1,0x2000,1,1); /* XINTF ZONE 0 */
GEL_MapAdd(0x4000,1,0x2000,1,1); /* XINTF ZONE 1 */
GEL_MapAdd(0x6000,1,0x1000,1,1); /* PF1 */
GEL_MapAddStr(0x7000,1,0x1000,"R|W|AS2",0); /* PF2 */
GEL_MapAdd(0x8000,1,0x2000,1,1); /* L0/L1 SARAM */
GEL_MapAdd(0x80000,1,0x80000,1,1); /* XINTF ZONE 2 */
GEL_MapAdd(0x100000,1,0x80000,1,1); /* XINTF ZONE 6 */
GEL_MapAdd(0x3d7800,1,0x800,1,0); /* OTP */
GEL_MapAdd(0x3d8000,1,0x20000,1,0); /* FLASH */
GEL_MapAdd(0x3f8000,1,0x2000,1,1); /* H0 SARAM */
/* Uncomment the map that corresponds to the MPNMC value. */
F2812_Boot_ROM_Map();
/* F2812_XINTF_Zone7_Map(); */
}
/* Map Boot ROM if MPNMC = 0 */
F2812_Boot_ROM_Map()
{
GEL_MapAdd(0x3ff000,0,0x1000,1,0); /* BOOT ROM */
GEL_MapAdd(0x3ff000,1,0x1000,1,0); /* BOOT ROM */
}
/* Map External Interface Zone 7 if MPNMC = 1 */
F2812_XINTF_Zone7_Map()
{
GEL_MapAdd(0x3fc000,0,0x4000,1,1); /* XINTF ZONE 7 */
GEL_MapAdd(0x3fc000,1,0x4000,1,1); /* XINTF ZONE 7 */
}
/* Enable DFT read/write for SARAM blocks */
Enable_DFT()
{
*0x950 = 0x0300; /* M0 */
*0x951 = 0x0300; /* M1 */
*0x952 = 0x0300; /* L0 */
*0x953 = 0x0300; /* L1 */
*0x954 = 0x0300; /* H0 */
}
menuitem "Watchdog";
hotmenu Disable_WD()
{
/* Enable WD override */
*0x7029 = *0x7029 | 0x0068;
*0x7025 = 0x0055;
*0x7025 = 0x00AA;
}
menuitem "Code Security Module"
hotmenu Unlock_CSM()
{
/* Assumes flash is erased */
*0xAE0 = 0xFFFF;
*0xAE1 = 0xFFFF;
*0xAE2 = 0xFFFF;
*0xAE3 = 0xFFFF;
*0xAE4 = 0xFFFF;
*0xAE5 = 0xFFFF;
*0xAE6 = 0xFFFF;
*0xAE7 = 0xFFFF;
/* Read the password locations */
XAR0 = *0x3F7FF8;
XAR0 = *0x3F7FF9;
XAR0 = *0x3F7FFA;
XAR0 = *0x3F7FFB;
XAR0 = *0x3F7FFC;
XAR0 = *0x3F7FFD;
XAR0 = *0x3F7FFE;
XAR0 = *0x3F7FFF;
}
menuitem "Addressing Modes";
hotmenu C27x_Mode()
{
AMODE = 0;
OBJMODE = 0;
}
hotmenu C28x_Mode()
{
AMODE = 0;
OBJMODE = 1;
}
hotmenu C2xLP_Mode()
{
AMODE = 1;
OBJMODE = 1;
}
上面的代码是DSP320F2812的一个GEL文件，上面添加了许多菜单项：
Scripts
- Initialize Memory Map
- F2812_Memory_Map
- Watchdog
- Disable_WD
- Code Security Module
- Unlock_CSM
- Addressing Modes
- C27x_Mode
- C28x_Mode
- C2xLP_Mode
结果的一个截图如下，
4. 关于GEL文件中的一些函数
StartUp
启动CCS时执行该函数，此时目标板可能还没有连接，该调用如果有对目标板的操作则会出错。
OnTargetConnect
连接目标板（点击Connect Target时）时执行。
OnReset
执行Reset命令时执行。
OnRestart
执行Restart命令时执行。
OnFileLoaded
执行Load File...命令时执行。
5. CCS自带GEL函数
参考《手把手教你DSP》，其中提到的函数都能在CCS 3.3中使用，但并不能保证能在更高版本中使用。
关于如何编写设备初始化的GEL，参考文档TI官方文档《Creating Device Initialization GEL Files》，链接为http://www.ti.com.cn/cn/lit/an/spraa74a/spraa74a.pdf。