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serige
Joined: 26 Nov 2007
Posts: 35
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 Posted: Mon Nov 26, 2007 8:55 am Post subject: allegrex full instruction set |
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hi,
I am looking at some psp assembly code, and I come across some unfamiliar instructions:
ins $s0, $zr, 0, 4
bnezl $s1, loc_00133D0C <--- a branch obviously, but not exactly sure what it does
can anyone tell me what are they? it would be nice if someone can give me the full instruction set (with explanations) so that i can look them up myself. |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Mon Nov 26, 2007 9:54 am Post subject: Re: allegrex full instruction set |
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| serige wrote: |
ins $s0, $zr, 0, 4
bnezl $s1, loc_00133D0C <--- a branch obviously, but not exactly sure what it does |
you can find those instructions in MIPS32 R2 documentation
ins $s0, $zr, 0, 4 ===> s0.bits[0..3] = 0;
branch has a delay slot (that is an instruction which follows the branch instruction) which is executed before jumping to target address
usually the instruction in the delay slot is always executed regardless whether the branch is taken (conditionnal branching).
But if a conditional branch has a 'l' suffix (which means 'likely') the instruction in the delay slot is executed if the branch is taken or skipped if not taken.
so if you have this :
bnezl $s1, loc
move $v0, $s1
===>
if (s1 != 0) { v0 = s1; goto loc; }
bnez $s1, loc
move $s1, $v0
===>
tmp = s1; s1 = v0; if (tmp != 0) { goto loc; }
beq r1, r2, loc : (r1 == r2)
bne r1, r2, loc : (r1 != r2)
beqz r1, loc : (r1 == 0)
bnez r1, loc : (r1 != 0)
bltz r1, loc : (r1 < 0)
bgez r1, loc : (r1 >= 0)
etc. |
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serige
Joined: 26 Nov 2007
Posts: 35
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| Posted: Mon Nov 26, 2007 11:04 am Post subject: |
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i am not sure if i got the ins instruction right
ins $1 $2 x y
so what it does it to clobber the the bits from index x to y-1 of the first register with that of the second register?
it doesn't seem I was able to find any info on this instruction from my google searches about the MIPS32 R2 documentation.
Thanks |
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serige
Joined: 26 Nov 2007
Posts: 35
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| Posted: Mon Nov 26, 2007 11:23 am Post subject: |
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| found it, thanks a lot! |
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moonlight
Joined: 26 Oct 2005
Posts: 567
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| Posted: Tue Nov 27, 2007 3:29 am Post subject: |
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| serige wrote: | i am not sure if i got the ins instruction right
ins $1 $2 x y
so what it does it to clobber the the bits from index x to y-1 of the first register with that of the second register?
it doesn't seem I was able to find any info on this instruction from my google searches about the MIPS32 R2 documentation.
Thanks |
Almost. It inserts y bits of $2 at the position x of $1.
Examples:
ins v0, v1, 0, 4 -> is equivalent to v0 = v0 | (v1 & 0xF)
ins v0, v1, 3, 9 -> equvialent to v0 = (v0 & 0xFFFFF007) | ((v1 & 0x1FF) << 3)
Too bad the psp sdk doesn't have a bulitin func for it.
Anyways I uploaded to you the mips doc i had somewhere:
http://rapidshare.com/files/72446657/MipsInstructionSetReference.pdf.html
It may miss some psp instruction like max and min, but ins, ext, seh, seb, etc should be there. |
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serige
Joined: 26 Nov 2007
Posts: 35
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| Posted: Wed Nov 28, 2007 5:22 pm Post subject: |
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can you use something like 'asm{ins v0, v1, 0, 4};' to execute this instruction?
i dont have the sdk installed in my computer anymore i can't verify this... |
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serige
Joined: 26 Nov 2007
Posts: 35
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| Posted: Wed Nov 28, 2007 5:25 pm Post subject: |
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| moonlight wrote: | | serige wrote: | i am not sure if i got the ins instruction right
ins $1 $2 x y
so what it does it to clobber the the bits from index x to y-1 of the first register with that of the second register?
it doesn't seem I was able to find any info on this instruction from my google searches about the MIPS32 R2 documentation.
Thanks |
Almost. It inserts y bits of $2 at the position x of $1.
Examples:
ins v0, v1, 0, 4 -> is equivalent to v0 = v0 | (v1 & 0xF)
ins v0, v1, 3, 9 -> equvialent to v0 = (v0 & 0xFFFFF007) | ((v1 & 0x1FF) << 3)
Too bad the psp sdk doesn't have a bulitin func for it.
Anyways I uploaded to you the mips doc i had somewhere:
http://rapidshare.com/files/72446657/MipsInstructionSetReference.pdf.html
It may miss some psp instruction like max and min, but ins, ext, seh, seb, etc should be there. |
Thanks a lot for your pdf! |
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Raphael
Joined: 17 Jan 2006
Posts: 646
Location: Germany
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moonlight
Joined: 26 Oct 2005
Posts: 567
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| Posted: Wed Nov 28, 2007 11:46 pm Post subject: |
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| It's a pity that instructions such as ins and ext don't have a builtin in the pspsdk, while other less useful like seb and seh have them. |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Thu Nov 29, 2007 7:10 am Post subject: |
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| Code: |
#define __asm_ins(rt, rs, lsb, len) \
({ \
int res = rt; \
__asm__ __volatile__ ( \
"ins %0, %1, %2, %3" \
: "+r"(res) /* output */ \
: "r"(rs), "i"(lsb), "i"(len) /* input */ \
); \
res; /* returns res */ \
})
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can be used this way :
int z = __asm_ins(x, y, 0, 4);
note that y can be a constant like __builtin_ins(x, 0, 0, 4);
and x and y can also be a complex expression like :
| Code: |
rgb565 = __asm_ins(
__asm_ins((r8>>3), (g8>>2), 5, 6),
(b8>>3), 5+6, 5
);
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fungos
Joined: 31 Oct 2007
Posts: 41
Location: cwb br
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J.F.
Joined: 22 Feb 2004
Posts: 2906
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