Float point display in arm-elf-sid

Float point display in arm-elf-sid

[Harry Hsin-Hua Pan(潘欣華)]

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Hi,
 
I've tried to build a SID with --target=arm-elf
Then I ran a test to displaying a float point.
But I got an incorrect display like following:
 
<arm-elf-sid-dir>/bin
$arm-elf-gcc test.c -o test.arm
$ ./arm-elf-sid -EL test.arm
hello! world
i=2
f=-2589673925853444962162817833395304976613376.000000
j=125
 
While tracing this issue, I found the arm7.cxx seems to not support "rotate right with extend" (RRX).
(Readers could refer to ARM DDI 0100E page A-17)
So I updated my arm7.cxx then re-built again.
Now I got correct display like following:
 
$ ./arm-elf-sid -EL test.arm
hello! world
i=2
f=123.456001
j=125
 
This issue seems to explain the strange result in the SID screen shot here.
http://sources.redhat.com/sid/screenshots/run-dhrystone.jpg
 
I attached my patch which was generated with the CVS snapshot in 20060325.
I didn't verified it to check whether there is another side effect.
So, would somebody like to verify this patch?
 
Regards,
Harry.
 
 
 

[-- Attachment #2: sid-20060325-patch.diff --]
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--- sid-20060325/sid/component/cgen-cpu/arm7t/arm7f.cxx	2004-08-04 23:42:00.000000000 +0800
+++ sid-20060325-patch/sid/component/cgen-cpu/arm7t/arm7f.cxx	2006-03-29 12:56:55.021225400 +0800
@@ -1443,7 +1443,11 @@
     case SHIFT_TYPE_LSL : return rm << shift;
     case SHIFT_TYPE_LSR : return (USI) rm >> shift;
     case SHIFT_TYPE_ASR : return rm >> shift;
-    case SHIFT_TYPE_ROR : return RORSI (rm, shift);
+    case SHIFT_TYPE_ROR : //return RORSI (rm, shift); // old
+        if (shift == 0) // it is RRX
+	    return ((USI)rm >> 1) | ((USI)this->hardware.h_cbit << 31);
+	else
+	    return RORSI (rm, shift);
     }
   abort();
 }

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#include <stdio.h>

static char hello[] = "hello! world";

int main(void)
{
	int i = 2;
	float f = 123.456;
	int j;
	
	printf("%s\n", hello);
	printf("i=%d\n", i);
check_point01:
	printf("f=%f\n", f);

	j = (int)f + i;

	printf("j=%d\n", j);
	return 0;
}

Re: Float point display in arm-elf-sid

[Frank Ch. Eigler]

Hi -

> While tracing this issue, I found the arm7.cxx seems to not support
> "rotate right with extend" (RRX).  [...]  So I updated my arm7.cxx
> then re-built again.  Now I got correct display like following:
> [...]

Nice work thanks!  I committed your patch, after checking the ARM7TDMI
docs and GNU AS's encoding logic.

- FChE