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authorCarl Shaw <carl.shaw@st.com>2008-09-05 16:36:19 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-09-08 10:35:05 +0900
commitb6ad1e8c3f76fcc5dee506d5e79e752d296ff745 (patch)
treec626da55bdfc3e19419856e086a5cad1dc4829c4 /arch/sh/kernel
parentf040ddaf4cfd28f25ea9d6a42d3c734d5c3f6798 (diff)
sh: Subnormal double to float conversion
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>
Diffstat (limited to 'arch/sh/kernel')
-rw-r--r--arch/sh/kernel/cpu/sh4/fpu.c25
-rw-r--r--arch/sh/kernel/cpu/sh4/softfloat.c29
2 files changed, 53 insertions, 1 deletions
diff --git a/arch/sh/kernel/cpu/sh4/fpu.c b/arch/sh/kernel/cpu/sh4/fpu.c
index 2d452f67fb8..2780917c008 100644
--- a/arch/sh/kernel/cpu/sh4/fpu.c
+++ b/arch/sh/kernel/cpu/sh4/fpu.c
@@ -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;
/*
@@ -417,6 +417,29 @@ static int ieee_fpe_handler(struct pt_regs *regs)
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;
}
return 0;
diff --git a/arch/sh/kernel/cpu/sh4/softfloat.c b/arch/sh/kernel/cpu/sh4/softfloat.c
index 828cb57cb95..2b747f3b02b 100644
--- a/arch/sh/kernel/cpu/sh4/softfloat.c
+++ b/arch/sh/kernel/cpu/sh4/softfloat.c
@@ -85,6 +85,7 @@ float64 float64_div(float64 a, float64 b);
float32 float32_div(float32 a, float32 b);
float32 float32_mul(float32 a, float32 b);
float64 float64_mul(float64 a, float64 b);
+float32 float64_to_float32(float64 a);
inline void add128(bits64 a0, bits64 a1, bits64 b0, bits64 b1, bits64 * z0Ptr,
bits64 * z1Ptr);
inline void sub128(bits64 a0, bits64 a1, bits64 b0, bits64 b1, bits64 * z0Ptr,
@@ -890,3 +891,31 @@ float64 float64_mul(float64 a, float64 b)
}
return roundAndPackFloat64(zSign, zExp, zSig0);
}
+
+/*
+ * -------------------------------------------------------------------------------
+ * Returns the result of converting the double-precision floating-point value
+ * `a' to the single-precision floating-point format. The conversion is
+ * performed according to the IEC/IEEE Standard for Binary Floating-point
+ * Arithmetic.
+ * -------------------------------------------------------------------------------
+ * */
+float32 float64_to_float32(float64 a)
+{
+ flag aSign;
+ int16 aExp;
+ bits64 aSig;
+ bits32 zSig;
+
+ aSig = extractFloat64Frac( a );
+ aExp = extractFloat64Exp( a );
+ aSign = extractFloat64Sign( a );
+
+ shift64RightJamming( aSig, 22, &aSig );
+ zSig = aSig;
+ if ( aExp || zSig ) {
+ zSig |= 0x40000000;
+ aExp -= 0x381;
+ }
+ return roundAndPackFloat32(aSign, aExp, zSig);
+}