DSP TMS320C6000基础学习（4）—— cmd文件分析

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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cmd文件主要用于完成链接的功能，因此可以在cmd文件中使用链接命令，比如：

-stack 0x200    设置栈大小为0x200字节

-heap 0x200     设置堆大小为0x200字节

-l rst67xx.lib  链接rst67xx.lib库

除了链接命令外，cmd 文件还包括MEMORY和SECTOINS两部分，分别用于存储区的划分和段的分配。

MEMORY划分的格式为：

L2SRAM    : o = 00000000h l = 00030000h  /* L2 SRAM 192K */

o表示起始地址，l表示存储区长度（以字节为单位）

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  > EXTERNALC6713_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 0x8000MEMORY{IRAMo = 0x00000000l = 0x00030000/* 192kB - Internal RAM */L2RAMo = 0x00030000l = 0x00010000/* 64kB - Internal RAM/CACHE */EMIFCE0o = 0x80000000l = 0x10000000/* SDRAM in 6713 DSK */EMIFCE1o = 0x90000000l = 0x10000000/* Flash/CPLD in 6713 DSK */EMIFCE2o = 0xA0000000l = 0x10000000/* Daughterboard in 6713 DSK */EMIFCE3o = 0xB0000000l = 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}