[avr-libc-dev] [bug #21805] boot.h: Use out instead of sts

[Shaun Jackman]

URL:
  <http://savannah.nongnu.org/bugs/?21805>

                 Summary: boot.h: Use out instead of sts
                 Project: AVR C Runtime Library
            Submitted by: sjackman
            Submitted on: Friday 12/14/2007 at 23:51
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Header files
                  Status: None
        Percent Complete: 0%
             Assigned to: None
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any

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Details:

>From boot.h:
    \todo From email with Marek: On smaller devices (all except
ATmega64/128),
    __SPM_REG is in the I/O space, accessible with the shorter "in" and
"out"
    instructions - since the boot loader has a limited size, this could be
an
    important optimization.

I'm writing a boot-loader that has to fit into the 256 byte boot-loader space
of the 8 kB parts. Here is my proposed solution to fix this matter. I've only
fixed the __boot_xxx_normal variants, but the same logic could easily be
extended to the __boot_xxx_alternate and __boot_xxx_extended variants.

Cheers,
Shaun

2007-12-14  Shaun Jackman  <address@hidden>

        * include/avr/boot.h (__boot_page_fill_normal,
        __boot_page_erase_normal, __boot_page_write_normal,
        __boot_rww_enable): Use an out instruction rather than an sts
        instruction when possible.




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File Attachments:


-------------------------------------------------------
Date: Friday 12/14/2007 at 23:51  Name: boot.diff  Size: 5kB   By: sjackman

<http://savannah.nongnu.org/bugs/download.php?file_id=14628>

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