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sh: Subnormal double to float conversion

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This patch adds support for the SH4 to convert a subnormal double
into a float by catching the FPE and implementing the FCNVDS
instruction in software.

Signed-off-by: Carl Shaw <carl.shaw@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Carl Shaw
2008-09-05 16:36:19 +09:00
committed by Paul Mundt
parent f040ddaf4c
commit b6ad1e8c3f
2 changed files with 53 additions and 1 deletions
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25
arch/sh/kernel/cpu/sh4/fpu.c
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@@ -36,7 +36,7 @@ extern unsigned long int float32_add(unsigned long int a, unsigned long int b);
extern unsigned long long float64_sub(unsigned long long a,
unsigned long long b);
extern unsigned long int float32_sub(unsigned long int a, unsigned long int b);
extern unsigned long int float64_to_float32(unsigned long long a);
static unsigned int fpu_exception_flags;
/*
@@ -415,6 +415,29 @@ static int ieee_fpe_handler(struct pt_regs *regs)
} else
return 0;
regs->pc = nextpc;
return 1;
} else if ((finsn & 0xf0bd) == 0xf0bd) {
/* fcnvds - double to single precision convert */
struct task_struct *tsk = current;
int m;
unsigned int hx;
m = (finsn >> 9) & 0x7;
hx = tsk->thread.fpu.hard.fp_regs[m];
if ((tsk->thread.fpu.hard.fpscr & FPSCR_CAUSE_ERROR)
&& ((hx & 0x7fffffff) < 0x00100000)) {
/* subnormal double to float conversion */
long long llx;
llx = ((long long)tsk->thread.fpu.hard.fp_regs[m] << 32)
| tsk->thread.fpu.hard.fp_regs[m + 1];
tsk->thread.fpu.hard.fpul = float64_to_float32(llx);
} else
return 0;
regs->pc = nextpc;
return 1;
}