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Message
From: Matjaz Breskvar<phoenix@o...>
Date: Tue May 31 22:05:04 CEST 2005
Subject: [openrisc] Difference Between Jump(l.j) and Jump and Link (l.jal)
* Balaji V. Iyer (bviyer@n...) wrote:
> Hi Everyone,
> What exactly is the difference between Jump and link and the Jump
> instruction? Don't they both do the same thing (according to the
> OpenRISC architecture manual where it says "32 Bit Implementation").
>
> For Example, let's say we have
>
> 100C: l.j 103233
> 1010: addi r3,r0,0x2
> 1014: ori r3,r11,0x0
> and
>
> 100C: l.jal 103233
> 1010: addi r3,r0,0x2
> 1014: ori r3,r11,0x0
>
>
> both of then should write 2 into R3 before jumping to 103233 and the R9
> for both the jumps will be set to 1014.. am I correct?
all true, but l.jal does an additionaly moves the address of next
instruction after the delay slot into r9 (the link register). this way you
simplify the function call/return (ie the return is just l.jr r9)
best regards,
p.
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