vfp: Handle flush-to-zero mode.

3 files changed, 98 insertions, 84 deletions

diff --git a/src/core/arm/skyeye_common/vfp/vfp_helper.h b/src/core/arm/skyeye_common/vfp/vfp_helper.h
index 6b3dae28..ccc0212a 100644
--- a/src/core/arm/skyeye_common/vfp/vfp_helper.h
+++ b/src/core/arm/skyeye_common/vfp/vfp_helper.h
@@ -35,6 +35,7 @@
 #include <cstdio>
 #include "common/common_types.h"
 #include "core/arm/skyeye_common/armdefs.h"
+#include "core/arm/skyeye_common/vfp/asm_vfp.h"
 
 #define do_div(n, base) {n/=base;}
 
@@ -236,33 +237,6 @@ struct vfp_single {
 #define vfp_single_packed_exponent(v) (((v) >> VFP_SINGLE_MANTISSA_BITS) & ((1 << VFP_SINGLE_EXPONENT_BITS) - 1))
 #define vfp_single_packed_mantissa(v) ((v) & ((1 << VFP_SINGLE_MANTISSA_BITS) - 1))
 
-// Unpack a single-precision float.  Note that this returns the magnitude
-// of the single-precision float mantissa with the 1. if necessary,
-// aligned to bit 30.
-static inline void vfp_single_unpack(vfp_single* s, s32 val)
-{
-    u32 significand;
-
-    s->sign = vfp_single_packed_sign(val) >> 16,
-    s->exponent = vfp_single_packed_exponent(val);
-
-    significand = (u32) val;
-    significand = (significand << (32 - VFP_SINGLE_MANTISSA_BITS)) >> 2;
-    if (s->exponent && s->exponent != 255)
-        significand |= 0x40000000;
-    s->significand = significand;
-}
-
-// Re-pack a single-precision float.  This assumes that the float is
-// already normalised such that the MSB is bit 30, _not_ bit 31.
-static inline s32 vfp_single_pack(vfp_single* s)
-{
-    u32 val = (s->sign << 16) +
-              (s->exponent << VFP_SINGLE_MANTISSA_BITS) +
-              (s->significand >> VFP_SINGLE_LOW_BITS);
-    return (s32)val;
-}
-
 enum : u32 {
     VFP_NUMBER     = (1 << 0),
     VFP_ZERO       = (1 << 1),
@@ -294,6 +268,39 @@ static inline int vfp_single_type(vfp_single* s)
     return type;
 }
 
+// Unpack a single-precision float.  Note that this returns the magnitude
+// of the single-precision float mantissa with the 1. if necessary,
+// aligned to bit 30.
+static inline void vfp_single_unpack(vfp_single* s, s32 val, u32* fpscr)
+{
+    s->sign = vfp_single_packed_sign(val) >> 16,
+    s->exponent = vfp_single_packed_exponent(val);
+
+    u32 significand = ((u32)val << (32 - VFP_SINGLE_MANTISSA_BITS)) >> 2;
+    if (s->exponent && s->exponent != 255)
+        significand |= 0x40000000;
+    s->significand = significand;
+
+    // If flush-to-zero mode is enabled, turn the denormal into zero.
+    // On a VFPv2 architecture, the sign of the zero is always positive.
+    if ((*fpscr & FPSCR_FLUSH_TO_ZERO) != 0 && (vfp_single_type(s) & VFP_DENORMAL) != 0) {
+        s->sign = 0;
+        s->exponent = 0;
+        s->significand = 0;
+        *fpscr |= FPSCR_IDC;
+    }
+}
+
+// Re-pack a single-precision float. This assumes that the float is
+// already normalised such that the MSB is bit 30, _not_ bit 31.
+static inline s32 vfp_single_pack(vfp_single* s)
+{
+    u32 val = (s->sign << 16) +
+              (s->exponent << VFP_SINGLE_MANTISSA_BITS) +
+              (s->significand >> VFP_SINGLE_LOW_BITS);
+    return (s32)val;
+}
+
 
 u32 vfp_single_normaliseround(ARMul_State* state, int sd, vfp_single* vs, u32 fpscr, u32 exceptions, const char* func);
 
@@ -328,24 +335,49 @@ struct vfp_double {
 #define vfp_double_packed_exponent(v) (((v) >> VFP_DOUBLE_MANTISSA_BITS) & ((1 << VFP_DOUBLE_EXPONENT_BITS) - 1))
 #define vfp_double_packed_mantissa(v) ((v) & ((1ULL << VFP_DOUBLE_MANTISSA_BITS) - 1))
 
+static inline int vfp_double_type(vfp_double* s)
+{
+    int type = VFP_NUMBER;
+    if (s->exponent == 2047) {
+        if (s->significand == 0)
+            type = VFP_INFINITY;
+        else if (s->significand & VFP_DOUBLE_SIGNIFICAND_QNAN)
+            type = VFP_QNAN;
+        else
+            type = VFP_SNAN;
+    } else if (s->exponent == 0) {
+        if (s->significand == 0)
+            type |= VFP_ZERO;
+        else
+            type |= VFP_DENORMAL;
+    }
+    return type;
+}
+
 // Unpack a double-precision float.  Note that this returns the magnitude
 // of the double-precision float mantissa with the 1. if necessary,
 // aligned to bit 62.
-static inline void vfp_double_unpack(vfp_double* s, s64 val)
+static inline void vfp_double_unpack(vfp_double* s, s64 val, u32* fpscr)
 {
-    u64 significand;
-
     s->sign = vfp_double_packed_sign(val) >> 48;
     s->exponent = vfp_double_packed_exponent(val);
 
-    significand = (u64) val;
-    significand = (significand << (64 - VFP_DOUBLE_MANTISSA_BITS)) >> 2;
+    u64 significand = ((u64)val << (64 - VFP_DOUBLE_MANTISSA_BITS)) >> 2;
     if (s->exponent && s->exponent != 2047)
         significand |= (1ULL << 62);
     s->significand = significand;
+
+    // If flush-to-zero mode is enabled, turn the denormal into zero.
+    // On a VFPv2 architecture, the sign of the zero is always positive.
+    if ((*fpscr & FPSCR_FLUSH_TO_ZERO) != 0 && (vfp_double_type(s) & VFP_DENORMAL) != 0) {
+        s->sign = 0;
+        s->exponent = 0;
+        s->significand = 0;
+        *fpscr |= FPSCR_IDC;
+    }
 }
 
-// Re-pack a double-precision float.  This assumes that the float is
+// Re-pack a double-precision float. This assumes that the float is
 // already normalised such that the MSB is bit 30, _not_ bit 31.
 static inline s64 vfp_double_pack(vfp_double* s)
 {
@@ -355,25 +387,6 @@ static inline s64 vfp_double_pack(vfp_double* s)
     return (s64)val;
 }
 
-static inline int vfp_double_type(vfp_double* s)
-{
-    int type = VFP_NUMBER;
-    if (s->exponent == 2047) {
-        if (s->significand == 0)
-            type = VFP_INFINITY;
-        else if (s->significand & VFP_DOUBLE_SIGNIFICAND_QNAN)
-            type = VFP_QNAN;
-        else
-            type = VFP_SNAN;
-    } else if (s->exponent == 0) {
-        if (s->significand == 0)
-            type |= VFP_ZERO;
-        else
-            type |= VFP_DENORMAL;
-    }
-    return type;
-}
-
 u32 vfp_estimate_sqrt_significand(u32 exponent, u32 significand);
 
 // A special flag to tell the normalisation code not to normalise.
diff --git a/src/core/arm/skyeye_common/vfp/vfpdouble.cpp b/src/core/arm/skyeye_common/vfp/vfpdouble.cpp
index d76d37fd..ab9fec39 100644
--- a/src/core/arm/skyeye_common/vfp/vfpdouble.cpp
+++ b/src/core/arm/skyeye_common/vfp/vfpdouble.cpp
@@ -291,7 +291,8 @@ static u32 vfp_double_fsqrt(ARMul_State* state, int dd, int unused, int dm, u32
     vfp_double vdm, vdd, *vdp;
     int ret, tm;
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
+
     tm = vfp_double_type(&vdm);
     if (tm & (VFP_NAN|VFP_INFINITY)) {
         vdp = &vdd;
@@ -473,7 +474,7 @@ static u32 vfp_double_fcvts(ARMul_State* state, int sd, int unused, int dm, u32
     u32 exceptions = 0;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
 
     tm = vfp_double_type(&vdm);
 
@@ -543,7 +544,7 @@ static u32 vfp_double_ftoui(ARMul_State* state, int sd, int unused, int dm, u32
     int tm;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
 
     /*
      * Do we have a denormalised number?
@@ -624,7 +625,7 @@ static u32 vfp_double_ftosi(ARMul_State* state, int sd, int unused, int dm, u32
     int tm;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     vfp_double_dump("VDM", &vdm);
 
     /*
@@ -896,11 +897,11 @@ vfp_double_multiply_accumulate(ARMul_State* state, int dd, int dn, int dm, u32 f
     struct vfp_double vdd, vdp, vdn, vdm;
     u32 exceptions;
 
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
     if (vdn.exponent == 0 && vdn.significand)
         vfp_double_normalise_denormal(&vdn);
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     if (vdm.exponent == 0 && vdm.significand)
         vfp_double_normalise_denormal(&vdm);
 
@@ -908,7 +909,7 @@ vfp_double_multiply_accumulate(ARMul_State* state, int dd, int dn, int dm, u32 f
     if (negate & NEG_MULTIPLY)
         vdp.sign = vfp_sign_negate(vdp.sign);
 
-    vfp_double_unpack(&vdn, vfp_get_double(state, dd));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dd), &fpscr);
     if (vdn.exponent == 0 && vdn.significand != 0)
         vfp_double_normalise_denormal(&vdn);
 
@@ -969,11 +970,11 @@ static u32 vfp_double_fmul(ARMul_State* state, int dd, int dn, int dm, u32 fpscr
     u32 exceptions;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
     if (vdn.exponent == 0 && vdn.significand)
         vfp_double_normalise_denormal(&vdn);
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     if (vdm.exponent == 0 && vdm.significand)
         vfp_double_normalise_denormal(&vdm);
 
@@ -990,11 +991,11 @@ static u32 vfp_double_fnmul(ARMul_State* state, int dd, int dn, int dm, u32 fpsc
     u32 exceptions;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
     if (vdn.exponent == 0 && vdn.significand)
         vfp_double_normalise_denormal(&vdn);
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     if (vdm.exponent == 0 && vdm.significand)
         vfp_double_normalise_denormal(&vdm);
 
@@ -1013,11 +1014,11 @@ static u32 vfp_double_fadd(ARMul_State* state, int dd, int dn, int dm, u32 fpscr
     u32 exceptions;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
     if (vdn.exponent == 0 && vdn.significand)
         vfp_double_normalise_denormal(&vdn);
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     if (vdm.exponent == 0 && vdm.significand)
         vfp_double_normalise_denormal(&vdm);
 
@@ -1035,11 +1036,11 @@ static u32 vfp_double_fsub(ARMul_State* state, int dd, int dn, int dm, u32 fpscr
     u32 exceptions;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
     if (vdn.exponent == 0 && vdn.significand)
         vfp_double_normalise_denormal(&vdn);
 
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
     if (vdm.exponent == 0 && vdm.significand)
         vfp_double_normalise_denormal(&vdm);
 
@@ -1063,8 +1064,8 @@ static u32 vfp_double_fdiv(ARMul_State* state, int dd, int dn, int dm, u32 fpscr
     int tm, tn;
 
     LOG_TRACE(Core_ARM11, "In %s\n", __FUNCTION__);
-    vfp_double_unpack(&vdn, vfp_get_double(state, dn));
-    vfp_double_unpack(&vdm, vfp_get_double(state, dm));
+    vfp_double_unpack(&vdn, vfp_get_double(state, dn), &fpscr);
+    vfp_double_unpack(&vdm, vfp_get_double(state, dm), &fpscr);
 
     vdd.sign = vdn.sign ^ vdm.sign;
 
diff --git a/src/core/arm/skyeye_common/vfp/vfpsingle.cpp b/src/core/arm/skyeye_common/vfp/vfpsingle.cpp
index a78bdc43..4dfe0254 100644
--- a/src/core/arm/skyeye_common/vfp/vfpsingle.cpp
+++ b/src/core/arm/skyeye_common/vfp/vfpsingle.cpp
@@ -330,7 +330,7 @@ static u32 vfp_single_fsqrt(ARMul_State* state, int sd, int unused, s32 m, u32 f
     struct vfp_single vsm, vsd, *vsp;
     int ret, tm;
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     tm = vfp_single_type(&vsm);
     if (tm & (VFP_NAN|VFP_INFINITY)) {
         vsp = &vsd;
@@ -498,7 +498,7 @@ static u32 vfp_single_fcvtd(ARMul_State* state, int dd, int unused, s32 m, u32 f
     int tm;
     u32 exceptions = 0;
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
 
     tm = vfp_single_type(&vsm);
 
@@ -563,7 +563,7 @@ static u32 vfp_single_ftoui(ARMul_State* state, int sd, int unused, s32 m, u32 f
     int rmode = fpscr & FPSCR_RMODE_MASK;
     int tm;
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     vfp_single_dump("VSM", &vsm);
 
     /*
@@ -643,7 +643,7 @@ static u32 vfp_single_ftosi(ARMul_State* state, int sd, int unused, s32 m, u32 f
     int rmode = fpscr & FPSCR_RMODE_MASK;
     int tm;
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     vfp_single_dump("VSM", &vsm);
 
     /*
@@ -925,11 +925,11 @@ vfp_single_multiply_accumulate(ARMul_State* state, int sd, int sn, s32 m, u32 fp
 
     v = vfp_get_float(state, sn);
     LOG_DEBUG(Core_ARM11, "s%u = %08x", sn, v);
-    vfp_single_unpack(&vsn, v);
+    vfp_single_unpack(&vsn, v, &fpscr);
     if (vsn.exponent == 0 && vsn.significand)
         vfp_single_normalise_denormal(&vsn);
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     if (vsm.exponent == 0 && vsm.significand)
         vfp_single_normalise_denormal(&vsm);
 
@@ -940,7 +940,7 @@ vfp_single_multiply_accumulate(ARMul_State* state, int sd, int sn, s32 m, u32 fp
 
     v = vfp_get_float(state, sd);
     LOG_DEBUG(Core_ARM11, "s%u = %08x", sd, v);
-    vfp_single_unpack(&vsn, v);
+    vfp_single_unpack(&vsn, v, &fpscr);
     if (vsn.exponent == 0 && vsn.significand != 0)
         vfp_single_normalise_denormal(&vsn);
 
@@ -1004,11 +1004,11 @@ static u32 vfp_single_fmul(ARMul_State* state, int sd, int sn, s32 m, u32 fpscr)
 
     LOG_DEBUG(Core_ARM11, "s%u = %08x", sn, n);
 
-    vfp_single_unpack(&vsn, n);
+    vfp_single_unpack(&vsn, n, &fpscr);
     if (vsn.exponent == 0 && vsn.significand)
         vfp_single_normalise_denormal(&vsn);
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     if (vsm.exponent == 0 && vsm.significand)
         vfp_single_normalise_denormal(&vsm);
 
@@ -1027,11 +1027,11 @@ static u32 vfp_single_fnmul(ARMul_State* state, int sd, int sn, s32 m, u32 fpscr
 
     LOG_DEBUG(Core_ARM11, "s%u = %08x", sn, n);
 
-    vfp_single_unpack(&vsn, n);
+    vfp_single_unpack(&vsn, n, &fpscr);
     if (vsn.exponent == 0 && vsn.significand)
         vfp_single_normalise_denormal(&vsn);
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     if (vsm.exponent == 0 && vsm.significand)
         vfp_single_normalise_denormal(&vsm);
 
@@ -1054,11 +1054,11 @@ static u32 vfp_single_fadd(ARMul_State* state, int sd, int sn, s32 m, u32 fpscr)
     /*
      * Unpack and normalise denormals.
      */
-    vfp_single_unpack(&vsn, n);
+    vfp_single_unpack(&vsn, n, &fpscr);
     if (vsn.exponent == 0 && vsn.significand)
         vfp_single_normalise_denormal(&vsn);
 
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsm, m, &fpscr);
     if (vsm.exponent == 0 && vsm.significand)
         vfp_single_normalise_denormal(&vsm);
 
@@ -1094,8 +1094,8 @@ static u32 vfp_single_fdiv(ARMul_State* state, int sd, int sn, s32 m, u32 fpscr)
 
     LOG_DEBUG(Core_ARM11, "s%u = %08x", sn, n);
 
-    vfp_single_unpack(&vsn, n);
-    vfp_single_unpack(&vsm, m);
+    vfp_single_unpack(&vsn, n, &fpscr);
+    vfp_single_unpack(&vsm, m, &fpscr);
 
     vsd.sign = vsn.sign ^ vsm.sign;