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Homebrew PS2, PSP & PS3 Development Discussions
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Kojima
Joined: 26 Jun 2006
Posts: 275
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 Posted: Sat Jul 08, 2006 5:20 am Post subject: From ps2 asm to psp asm. |
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Can anyone spot why this doesn't work?
It's a simple multply test that works perfectly on the ps2, but on the psp (using the c++ compiler not c) it fails, saying mult $5,$5,$3 is an illegal operand.
| Code: |
void AddTest()
{
int num1=5;
int num2=10;
int out=0;
asm __volatile__ ("\n\
mult %0,%1,%2\n\ // <<<<
":"=r"(out):"r"(num1),"r"(num2));
printf("Result:%d \n",out);
}
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Are there major differences between ps2/psp asm in inline usage or do I just need to modify it a little? |
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TyRaNiD
Joined: 18 Jan 2004
Posts: 918
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| Posted: Sat Jul 08, 2006 6:04 am Post subject: |
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| Probably because on the allegrex it only supports the mult s, t form with the result going to the HI and LO regs I would expect. |
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Kojima
Joined: 26 Jun 2006
Posts: 275
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| Posted: Sat Jul 08, 2006 6:12 am Post subject: |
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| ah ok, thanks. |
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Kojima
Joined: 26 Jun 2006
Posts: 275
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| Posted: Sat Jul 08, 2006 6:34 pm Post subject: |
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Anyone know why this doesn't work on psp?
ori $15,$0,%1\n\
I'm just trying to set register 15 with the value of operand 1 but it says "Error:Register value used as an expression"
Has ori changed from ps2 too? |
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TyRaNiD
Joined: 18 Jan 2004
Posts: 918
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| Posted: Sat Jul 08, 2006 7:33 pm Post subject: |
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| no ori is the same as it ever was, the third parameter is an immediate value not the a register, if you use a register then use normal or. |
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Kojima
Joined: 26 Jun 2006
Posts: 275
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| Posted: Sat Jul 08, 2006 7:54 pm Post subject: |
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| Whoops, ok thanks. Still learning as I go. |
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Kojima
Joined: 26 Jun 2006
Posts: 275
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| Posted: Sat Jul 08, 2006 9:22 pm Post subject: |
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Can anyone see why this pice of asm hangs?
| Code: |
num1 =5;
num2 = 10;
out = 0;
to = 5;
asm __volatile__ ("\n\
ori $5,$0,0\n\
ori $17,$0,0\n\
loop:\n\
mul %1,%2\n\
mflo $16\n\
addu $19,$16,$17\n\
move $17,$19\n\
addu $5,$5,1\n\
bne $5,%3,loop\n\
nop\n\
move %0,$17\n\
":"=r"(out):"r"(num1),"r"(num2),"r"(to));
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in c++ terms it's only doing this,
| Code: |
int num1=5;
int num2=10;
int out=0;
int to = 5;
float r17,r16;
r16=0;
r17=0;
for(int i=0;i<to;i++)
{
float res = num1*num2;
r16 = res;
r17 = r16+r17;
}
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Saotome
Joined: 03 Apr 2004
Posts: 182
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| Posted: Sat Jul 08, 2006 10:56 pm Post subject: |
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I think it's because of this one:
the third parameter is an immediate but you're using addu instead of addiu. I believe in this case it's as if you're using addu $5,$5,$1 and if $1 != 1 then it doesn't work like it should ;)
_________________
infj |
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Kojima
Joined: 26 Jun 2006
Posts: 275
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| Posted: Sun Jul 09, 2006 12:54 am Post subject: |
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Thanks, still hangs though :)
Here's my new attempt at it,
| Code: |
void AddTest()
{
int num1=5;
int num2=10;
int out=0;
int to = 5;
float r17,r16;
r16=0;
r17=0;
for(int i=0;i<to;i++)
{
float res = num1*num2;
r16 = res;
r17 = r16+r17;
}
printf("C Res:%f",r17);
num1 =5;
num2 = 10;
out = 0;
to = 5;
asm __volatile__ ("\n\
ori $5,$0,0\n\
ori $17,$0,0\n\
loop:\n\
mul %1,%2\n\
mflo $16\n\
addu $19,$16,$17\n\
move $17,$19\n\
addiu $5,$5,1\n\
bne $5,%3,loop\n\
nop\n\
move %0,$17\n\
":"=r"(out):"r"(num1),"r"(num2),"r"(to));
printf("Asm Result:%d \n",out);
}
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It doesn't just hang, the psp resets, and the power light blinks on/off, I guess indicating there was a fatal error, then i have to hard reset. |
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