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What's the best way to put a webpage into flash

ToddMullanix
Guru* 96960 points

I'd like to put a static webpage into flash memory (to save RAM) on a M3 device. I'm using codegen 4.9.1.

The webpage is simply a char array:

    unsigned char DEFAULT[676] = { 0x3C, 0x21, 0x44, 0x4F, ...}

I tried putting the array into a data section and place it in the linker file

main.c:
    #pragma DATA_SECTION(DEFAULT, ".webpage")

link.cmd
    .webpage    : > FLASH

The array was placed in flash, but was all 0xff. I figure this is because it is initialized data, so will be set via cinit records during startup...that's a problem since it is in flash.

I tried putting the the array into .text (which is placed into flash also)

    #pragma DATA_SECTION(DEFAULT, ".text")

This worked, but seemed a little dodgy.

Using CODE_SECTION also worked

    #pragma CODE_SECTION(DEFAULT, ".webpage")

I'm leaning toward using CODE_SECTION (with a big comment!). Is there a better approach?

Thanks,
Todd

  • 0
    TI__Guru* 96960 points

    Oops, just show the compiler warning when I do "#pragma CODE_SECTION(DEFAULT, ".webpage")":

        "demo.c", line 71: warning: pragma CODE_SECTION can only be applied to a function definition, not "DEFAULT" (declared at line 2 of "default.h")

    Looks like I'm back to "#pragma DATA_SECTION(DEFAULT, ".text")" unless someone has a better idea.

    Thanks,
    Todd

  • 0
    TI__Guru* 84225 points

    Try declaring the array const to avoid cinit records:

    const unsigned char DEFAULT[676] = { 0x3C, 0x21, 0x44, 0x4F, ...};
  • 0 in reply to Archaeologist
    TI__Guru* 96960 points

    Sorry, I forgot to mention that I'm using a tool to generate the file that contains the array. It should put const, but doesn't. I'll see if I can get the tool changed. I'm a nervous about manually changing the generated file since I know I'll forget to do if I change the page. I probably code add the "const" as part of the build-system until the tool is fixed...

  • 0 in reply to ToddMullanix
    TI__Expert 4540 points

    You can also mark an output section as NOINIT in the linker command file. A section marked NOINIT will be direct initialized in the output file.

     .webpage: > FLASH type=NOINIT