ADSP21489工程中LDF文件配置详解

一直都没有搞懂LDF文件是怎么回事,后续翻到这个文档<cces-LinkerUtilities-manual.pdf>才认真的看了一下

存储空间分布表

MEMORY
{
   /* ADSP-21489 MEMORY MAP.
   **
   ** The SHARC 21489 has 5Mbit RAM in total.
   **
   ** -------------------------- BLOCK 0 ---------------------------------------
   ** 0x0008 C000 to 0x0009 3FFF  Normal word (48) Space (1.5 Mbit RAM)
   ** 0x0009 2000 to 0x0009 DFFF  Normal word (32) Space (1.5 Mbit RAM)
   ** 0x0012 4000 to 0x0013 BFFF  Short word  (16) Space (1.5 Mbit RAM)
   **
   ** Notes:
   ** 1) The interrupt Vector Table (IVT) code is placed in internal memory
   **    by default and has to use ISA (NW, 48 bit) instructions.
   ** 2) The loader kernel uses 256 ISA instructions from the start of the 
   **    IVT. The final action it does is to load the application code to these
   **    address overwriting it's own code. The application code in these
   **    addresses therefore must also be ISA instructions. Do not put 
   **    VISA (SW) instructions in these 256 locations.
   */
   mem_iv_code             { TYPE(PM RAM) START(0x0008C000) END(0x0008C0A7) WIDTH(48) }
   mem_block0_nwco         { TYPE(PM RAM) START(0x0008C0A8) END(0x0008C0FF) WIDTH(48) }
   mem_block0_sw16         { TYPE(SW RAM) START(0x00124300) END(0x0013BFFF) WIDTH(16) }

   /*
   ** -------------------------- BLOCK 1 ---------------------------------------
   ** 0x000A C000 to 0x000B 3FFF  Normal word (48) Space (1.5 Mbit RAM)
   ** 0x000B 2000 to 0x000B DFFF  Normal word (32) Space (1.5 Mbit RAM)
   ** 0x0016 4000 to 0x0017 BFFF  Short word (16)  Space (1.5 Mbit RAM)
   */
   mem_block1_dm32         { TYPE(DM RAM) START(0x000B2000) END(0x000BDFFF) WIDTH(32) }

   /*
   ** -------------------------- BLOCK 2 ---------------------------------------
   ** 0x000C 0000 to 0x000C 5554  Normal word (48) Space (1 Mbit RAM)
   ** 0x000C 0000 to 0x000C 7FFF  Normal word (32) Space (1 Mbit RAM)
   ** 0x0018 0000 to 0x0018 FFFF  Short word (16) Space (1 Mbit RAM)
   */
   mem_block2_pm32         { TYPE(PM RAM) START(0x000C0000) END(0x000C7FFF) WIDTH(32) }

   /*
   ** -------------------------- BLOCK 3 ---------------------------------------
   ** 0x000E 0000 to 0x000E 5554  Normal word (48) Space (1 Mbit RAM)
   ** 0x000E 0000 to 0x000E 7FFF  Normal word (32) Space (1 Mbit RAM)
   ** 0x001C 0000 to 0x001C FFFF  Short word (16)  Space (1 Mbit RAM)
   */
   mem_block3_dm32         { TYPE(DM RAM) START(0x000E0000) END(0x000E7FFF) WIDTH(32) }
   mem_sram                { TYPE(DM RAM ASYNCHRONOUS) START(0x0C000000) END(0x0C01FFFF) WIDTH(8) }
   mem_flash               { TYPE(DM RAM ASYNCHRONOUS) START(0x04000000) END(0x043FFFFF) WIDTH(8) }
   
   /*$VDSG<insert-new-memory-segments>                          */
   /* Text inserted between these $VDSG comments will be preserved */
   mem_block0_dm32         { TYPE(DM RAM) START(0x0009DA00) END(0x0009DFFF) WIDTH(32) }   
   mem_block3_dm48         { TYPE(DM RAM) START(0x000E0000) END(0x000E17FF) WIDTH(48) }
   mem_sdram_dmda1         { TYPE(DM RAM) START(0x00660000) END(0x00666BFF) WIDTH(16) }        
   /*$VDSG<insert-new-memory-segments>                          */
   
} /* MEMORY */

问题1:mem_block0_sw16的含义

表示片上空间block0段定义为16bit时的存储空间,ADSP21489片上的5Mbit RAM大小一共被分配成4个block,存储分配如下

BLOCK 0 = 1.5Mbit

BLOCK 1 = 1.5Mbit

BLOCK 2 = 1Mbit

BLOCK 3 = 1Mbit

合计5Mbit 

问题2:DM和PM的表面意义就是数据和程序空间的意思,但是数据空间是指的存储数据,那么程序空间是指在RAM上存储程序代码吗?

问题3:解释一下在ldf中的section是啥意思

#pragma section("ss_fw_code_fast")
void DelayMs(int nCount)
{
    int i = 0;

    for (i = 0; i < nCount; i++)
    {
        NOP;
    }
}

在LDF文件中又经常看见如下

INPUT_SECTIONS( $OBJECTS(iv_code) )

INPUT_SECTIONS( $OBJS_LIBS(seg_int_code seg_init seg_pmco) )

这里个人理解借用TI DSP的cmd文件进行理解一下

{ input_sections } —— 输入段，其语法如下：花括号“{}”中是输入段名。这里对输入段和输出段做一个区分，每一个C语言文件经过编译都会生成若干个段，多个汇编语言或C语言文件生成的段大都是同名的，常见的的段有如.cinit、.ebss等，这些都属于输入段。这些归属于不同文件的输入段，在CMD文件的指示下，会被链接器链接在一起生成输出段。
 

问题4:解释一下在ldf中的INPUT_SECTIONS( $OBJS_LIBS(seg_int_code_sw seg_int_code) )中各种美元符$后的标志的意思

$OBJS_LIBS(seg_int_code seg_init seg_pmco)

 $OBJECTS(ss_block0_data) $LIBRARIES(ss_block0_data)

os_mem1 {
 INPUT_SECTIONS($OBJECTS(program))
} >mem1
os_mem2 {
 INPUT_SECTIONS($OBJECTS(program))
} >mem2

找了一下原文解释

In the above example, if some of the input sections included in $OBJECTS(program) do not fit in os_mem1,
the linker will try to map them into os_mem2.

在上述示例中，如果$OBJECTS（program）中包含的一些输入部分不适合os_mem1，链接器将尝试将它们映射到os_mem2。

问题5:PM和SW是什么意思

• PM - program memory, contains 6 bytes per word.

• DM - data memory, contains 4 bytes per word.

• DATA64 - contains 8 bytes per word.

• SW - contains 2 bytes per word. ---- __SHORT_WORD_CODE__

问题6:ldf中一些关键的段,不可修改