math_efp.c: Fixed SPE data type conversion failure

math_efp.c: Fixed SPE data type conversion failure

[Shan Hai]

The following test case failed on Powerpc sbc8548 with CONFIG_SPE

static float fm;
static signed int si_min = (-2147483647 - 1);
static unsigned int ui;
int main()
{
        fm = (float) si_min; ;
        ui = (unsigned int)fm;
        printf("ui=%d, should be %d\n", ui, si_min);

        return 0;
}
Result: ui=-1, should be -2147483648

The reason is failure to emulate the minus float to unsigned integer conversion 
instruction in the SPE driver.

[PATCH] Fix SPE float to integer conversion failure

[Shan Hai]

Conversion from float to integer should based on both the instruction
encoding and the sign of the operand.

Signed-off-by: Shan Hai <shan.hai@windriver.com>
---
 arch/powerpc/math-emu/math_efp.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/math-emu/math_efp.c b/arch/powerpc/math-emu/math_efp.c
index 41f4ef3..64faf10 100644
--- a/arch/powerpc/math-emu/math_efp.c
+++ b/arch/powerpc/math-emu/math_efp.c
@@ -320,7 +320,8 @@ int do_spe_mathemu(struct pt_regs *regs)
 			} else {
 				_FP_ROUND_ZERO(1, SB);
 			}
-			FP_TO_INT_S(vc.wp[1], SB, 32, ((func & 0x3) != 0));
+			FP_TO_INT_S(vc.wp[1], SB, 32,
+					(((func & 0x3) != 0) || SB_s));
 			goto update_regs;
 
 		default:
@@ -458,7 +459,8 @@ cmp_s:
 			} else {
 				_FP_ROUND_ZERO(2, DB);
 			}
-			FP_TO_INT_D(vc.wp[1], DB, 32, ((func & 0x3) != 0));
+			FP_TO_INT_D(vc.wp[1], DB, 32,
+					(((func & 0x3) != 0) || DB_s));
 			goto update_regs;
 
 		default:
@@ -589,8 +591,10 @@ cmp_d:
 				_FP_ROUND_ZERO(1, SB0);
 				_FP_ROUND_ZERO(1, SB1);
 			}
-			FP_TO_INT_S(vc.wp[0], SB0, 32, ((func & 0x3) != 0));
-			FP_TO_INT_S(vc.wp[1], SB1, 32, ((func & 0x3) != 0));
+			FP_TO_INT_S(vc.wp[0], SB0, 32,
+					(((func & 0x3) != 0) || SB0_s));
+			FP_TO_INT_S(vc.wp[1], SB1, 32,
+					(((func & 0x3) != 0) || SB1_s));
 			goto update_regs;
 
 		default:
-- 
1.7.0.2

Re: [PATCH] Fix SPE float to integer conversion failure

[Kumar Gala]

On Nov 16, 2010, at 8:28 PM, Shan Hai wrote:

> Conversion from float to integer should based on both the instruction
> encoding and the sign of the operand.
> 
> Signed-off-by: Shan Hai <shan.hai@windriver.com>
> ---
> arch/powerpc/math-emu/math_efp.c |   12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)

applied

- k