DSP中的CMD文件是链接命令文件（Linker Command File），以.cmd为后缀。


在分析cmd文件之前，必需先了解
（1）DSP具体芯片的内存映射（Memory Map）
（2）知道点链接的知识，知道C程序中段的概念
（3）知道RAM,Flash等存储模块的区别


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1. coff目标文件
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coff是一种流行的二进制可执行文件格式，在CCS v5中扩展名为.out，可以直接
下载到芯片中。可执行文件包括段头、可执行代码、初始化数据、可重定位信息
和符号表字符串表等信息。
编译器处理段的过程为：
（1）把每个源文件都编译成独立目标文件(.obj)，每个目标文件都有自己的段
（2）链接器将目标文件中相同段名的部分连接在一起，生成最终的coff可执行文件
CCS v5中的Compile Files完成功能（1），Build完成功能（2）。


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2. TMS320C6713内存映射
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3. 自定义代码段和数据段
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// 将symbol分配到section name指示的数据段
#pragma DATA_SECTION(symbol, "section name");
// 将symbol分配到section name指示的代码段
#pragma CODE_SECTION(symbol, "section name");
常常结合结构体定义symbol，如下，
volatile struct Symbol symbol; // Symbol预先定义好的描述特定外设的结构


比如，对于C6713中的Timer0外设，做如下定义，
struct Timer0 { ... } #pragma DATA_SECTION(C6713_Timer0, "C6713_Timer0_cmd"); volatile struct Timer0 C6713_Timer0;
"C6713_Timer0_cmd"将在cmd文件中分配空间。


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4. cmd文件
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一个简单的例子（TMS320C6713为例，不同芯片不同），外设只添加了Timer0:
MEMORY { L2SRAM : o = 00000000h l = 00030000h /* L2 SRAM 192K */ L2CACHE : o = 00030000h l = 00010000h /* L2 Cache 64 K */ /* Peripheral */ CPU_TIMER0 : o = 01940000h l = 00040000 /* Timer0 */ EXTERNAL : o = 80000000h l = 80010000h } SECTIONS { /* Allocate program areas */ .text > L2SRAM /* code segment */ .cinit > L2SRAM /* init segment */ /* Allocate data areas */ .stack > L2SRAM .far > L2SRAM .switch > L2SRAM /* C switch table */ .tables > L2SRAM .data > L2SRAM /* data segment */ .bss > L2SRAM /* data that haven't init */ .sysmem > L2SRAM .const > L2SRAM /* string, const ... */ .cio > L2SRAM .buffers > EXTERNAL C6713_Timer0_cmd > CPU_TIMER0 /* Timer 0 */ }
cmd文件包括2部分 —— MEMORY与SECTIONS
MEMORY完成地址空间的划分；
SECTIONS完成地址空间的分配到具体用途（除了程序中通用段之外还可以有自定义段）。


NOTES: 平时开发时都是将程序下载到RAM空间，当要发布时需要下载到Flash空间，
此处为SRAM的cmd文件，Flash的cmd文件有所不同。


下面是TI公司DSK的cmd，可以直接参考， /****************************************************************************/ /* C6713.cmd */ /* Copyright (c) 2010 Texas Instruments Incorporated */ /* */ /* Description: This file is a sample linker command file that can be */ /* used for linking programs built with the C compiler and */ /* running the resulting .out file on an TMS320C6713 */ /* device. Use it as a guideline. You will want to */ /* change the memory layout to match your specific C6xxx */ /* target system. You may want to change the allocation */ /* scheme according to the size of your program. */ /* */ /****************************************************************************/ -stack 0x2000 -heap 0x8000 MEMORY { IRAM o = 0x00000000 l = 0x00030000 /* 192kB - Internal RAM */ L2RAM o = 0x00030000 l = 0x00010000 /* 64kB - Internal RAM/CACHE */ EMIFCE0 o = 0x80000000 l = 0x10000000 /* SDRAM in 6713 DSK */ EMIFCE1 o = 0x90000000 l = 0x10000000 /* Flash/CPLD in 6713 DSK */ EMIFCE2 o = 0xA0000000 l = 0x10000000 /* Daughterboard in 6713 DSK */ EMIFCE3 o = 0xB0000000 l = 0x10000000 /* Daughterboard in 6713 DSK */ } SECTIONS { .text > IRAM .stack > IRAM .bss > IRAM .cio > IRAM .const > IRAM .data > IRAM .switch > IRAM .sysmem > IRAM .far > IRAM .args > IRAM .ppinfo > IRAM .ppdata > IRAM /* COFF sections */ .pinit > IRAM .cinit > IRAM /* EABI sections */ .binit > IRAM .init_array > IRAM .neardata > IRAM .fardata > IRAM .rodata > IRAM .c6xabi.exidx > IRAM .c6xabi.extab > IRAM }

下面再给出一个TMS320F2818的完整cmd文件例子，与6713有所不同，比如16进制格式
表示，MEMORY和SECTIONS书写等。
MEMORY { PAGE 0 : PRAMH0 : origin = 0x3f8000, length = 0x001000 PAGE 1 : /* SARAM */ RAMM0 : origin = 0x000000, length = 0x000400 RAMM1 : origin = 0x000400, length = 0x000400 /* Peripheral Frame 0: */ DEV_EMU : origin = 0x000880, length = 0x000180 FLASH_REGS : origin = 0x000A80, length = 0x000060 CSM : origin = 0x000AE0, length = 0x000010 XINTF : origin = 0x000B20, length = 0x000020 CPU_TIMER0 : origin = 0x000C00, length = 0x000008 CPU_TIMER1 : origin = 0x000C08, length = 0x000008 CPU_TIMER2 : origin = 0x000C10, length = 0x000008 PIE_CTRL : origin = 0x000CE0, length = 0x000020 PIE_VECT : origin = 0x000D00, length = 0x000100 /* Peripheral Frame 1: */ ECAN_A : origin = 0x006000, length = 0x000100 ECAN_AMBOX : origin = 0x006100, length = 0x000100 /* Peripheral Frame 2: */ SYSTEM : origin = 0x007010, length = 0x000020 SPI_A : origin = 0x007040, length = 0x000010 SCI_A : origin = 0x007050, length = 0x000010 XINTRUPT : origin = 0x007070, length = 0x000010 GPIOMUX : origin = 0x0070C0, length = 0x000020 GPIODAT : origin = 0x0070E0, length = 0x000020 ADC : origin = 0x007100, length = 0x000020 EV_A : origin = 0x007400, length = 0x000040 EV_B : origin = 0x007500, length = 0x000040 SPI_B : origin = 0x007740, length = 0x000010 SCI_B : origin = 0x007750, length = 0x000010 MCBSP_A : origin = 0x007800, length = 0x000040 /* CSM Password Locations */ CSM_PWL : origin = 0x3F7FF8, length = 0x000008 /* SARAM */ DRAMH0 : origin = 0x3f9000, length = 0x001000 } SECTIONS { /* Allocate program areas: */ .reset : > PRAMH0, PAGE = 0 .text : > PRAMH0, PAGE = 0 .cinit : > PRAMH0, PAGE = 0 /* Allocate data areas: */ .stack : > RAMM1, PAGE = 1 .bss : > DRAMH0, PAGE = 1 .ebss : > DRAMH0, PAGE = 1 .const : > DRAMH0, PAGE = 1 .econst : > DRAMH0, PAGE = 1 .sysmem : > DRAMH0, PAGE = 1 /* Allocate Peripheral Frame 0 Register Structures: */ DevEmuRegsFile : > DEV_EMU, PAGE = 1 FlashRegsFile : > FLASH_REGS, PAGE = 1 CsmRegsFile : > CSM, PAGE = 1 XintfRegsFile : > XINTF, PAGE = 1 CpuTimer0RegsFile : > CPU_TIMER0, PAGE = 1 CpuTimer1RegsFile : > CPU_TIMER1, PAGE = 1 CpuTimer2RegsFile : > CPU_TIMER2, PAGE = 1 PieCtrlRegsFile : > PIE_CTRL, PAGE = 1 PieVectTable : > PIE_VECT, PAGE = 1 /* Allocate Peripheral Frame 2 Register Structures: */ ECanaRegsFile : > ECAN_A, PAGE = 1 ECanaMboxesFile : > ECAN_AMBOX PAGE = 1 /* Allocate Peripheral Frame 1 Register Structures: */ SysCtrlRegsFile : > SYSTEM, PAGE = 1 SpiaRegsFile : > SPI_A, PAGE = 1 SciaRegsFile : > SCI_A, PAGE = 1 XIntruptRegsFile : > XINTRUPT, PAGE = 1 GpioMuxRegsFile : > GPIOMUX, PAGE = 1 GpioDataRegsFile : > GPIODAT PAGE = 1 AdcRegsFile : > ADC, PAGE = 1 EvaRegsFile : > EV_A, PAGE = 1 EvbRegsFile : > EV_B, PAGE = 1 ScibRegsFile : > SCI_B, PAGE = 1 McbspaRegsFile : > MCBSP_A, PAGE = 1 /* CSM Password Locations */ CsmPwlFile : > CSM_PWL, PAGE = 1 }