GCC（AVR）汇编：减去标签地址

发布于 2024-11-28 10:03:30 字数 100 浏览 2 评论 0原文

我正在尝试完成：

LABEL:
....
subi r18, LABEL

我需要从寄存器中减去标签的地址。我该怎么做？

原文

I am trying to accomplish:

LABEL:
....
subi r18, LABEL

I need to subtract address of a label from a register. How do I do that?

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心房敞 2024-12-05 10:03:30

subi r16, pm_lo8(LABEL)
sbci r17, pm_hi8(LABEL)

正如 avrfreaks 上的回答：
http://www.avrfreaks.net/index .php?name=PNphpBB2&file=viewtopic&p=857982#857982

参考文档：
http://sourceware.org/binutils/docs-2.21/as/AVR_002dModifiers .html#AVR_002d修饰符

subi r16, pm_lo8(LABEL)
sbci r17, pm_hi8(LABEL)

as answered on avrfreaks:
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=857982#857982

reference document:
http://sourceware.org/binutils/docs-2.21/as/AVR_002dModifiers.html#AVR_002dModifiers

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天涯离梦残月幽梦 2024-12-05 10:03:30

注意：我对 AVR 汇编器不太熟悉，这只是我通过阅读一些网页可以得出的结论。我还假设您的地址是 16 位的。

; Address you wish to subtract the label from in R16 (low):R17 (high)

SUBI R16, LOW(LABEL)
SBCI R17, HIGH(LABEL) ; Omit this part if you have < 256 Bytes of ram

Note: I'm not that familiar with AVR assembler, this is just what I could gauge from reading a few webpages. I'm also assuming that your addresses are 16-bit.

; Address you wish to subtract the label from in R16 (low):R17 (high)

SUBI R16, LOW(LABEL)
SBCI R17, HIGH(LABEL) ; Omit this part if you have < 256 Bytes of ram

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