From 54da0e1be7a9c90b4225ac29cf5b5c8b4ec8304c Mon Sep 17 00:00:00 2001
From: Nicolas Brunie <nibrunie@gmail.com>
Date: Sat, 12 Aug 2023 10:34:58 +0200
Subject: Fixing dummy bf16_to_f32 conversion

---
 source/RISCV/specialize.h  |  8 ++++++++
 source/bf16_to_f32.c       | 42 +++++++++++++++++++++++++++++++++++++++++-
 source/include/internals.h |  3 ++-
 3 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/source/RISCV/specialize.h b/source/RISCV/specialize.h
index ec9eda2..cb95900 100644
--- a/source/RISCV/specialize.h
+++ b/source/RISCV/specialize.h
@@ -103,6 +103,14 @@ struct commonNaN { char _unused; };
 #define softfloat_f16UIToCommonNaN( uiA, zPtr ) if ( ! ((uiA) & 0x0200) ) softfloat_raiseFlags( softfloat_flag_invalid )
 
 /*----------------------------------------------------------------------------
+| Assuming 'uiA' has the bit pattern of a 16-bit BF16 floating-point NaN, converts
+| this NaN to the common NaN form, and stores the resulting common NaN at the
+| location pointed to by 'zPtr'.  If the NaN is a signaling NaN, the invalid
+| exception is raised.
+*----------------------------------------------------------------------------*/
+#define softfloat_bf16UIToCommonNaN( uiA, zPtr ) if ( ! ((uiA) & 0x0040) ) softfloat_raiseFlags( softfloat_flag_invalid )
+
+/*----------------------------------------------------------------------------
 | Converts the common NaN pointed to by 'aPtr' into a 16-bit floating-point
 | NaN, and returns the bit pattern of this value as an unsigned integer.
 *----------------------------------------------------------------------------*/
diff --git a/source/bf16_to_f32.c b/source/bf16_to_f32.c
index 175d0d4..a30006a 100644
--- a/source/bf16_to_f32.c
+++ b/source/bf16_to_f32.c
@@ -44,13 +44,53 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 float32_t bf16_to_f32( bfloat16_t a )
 {
     union ui16_bf16 uA;
+    uint_fast16_t uiA;
+    bool sign;
+    int_fast16_t exp;
+    uint_fast16_t frac;
+    struct commonNaN commonNaN;
+    uint_fast32_t uiZ;
+    struct exp8_sig16 normExpSig;
     union ui32_f32 uZ;
 
     /*------------------------------------------------------------------------
     *------------------------------------------------------------------------*/
     uA.f = a;
-    uZ.ui = (uint32_t) uA.ui << 16;
+    uiA = uA.ui;
+    sign = signBF16UI( uiA );
+    exp  = expBF16UI( uiA );
+    frac = fracBF16UI( uiA );
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    // NaN or Inf
+    if ( exp == 0xFF ) {
+        if ( frac ) {
+            softfloat_bf16UIToCommonNaN( uiA, &commonNaN );
+            uiZ = softfloat_commonNaNToF32UI( &commonNaN );
+        } else {
+            uiZ = packToF32UI( sign, 0xFF, 0 );
+        }
+        goto uiZ;
+    }
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    if ( ! exp ) {
+        if ( ! frac ) {
+            uiZ = packToF32UI( sign, 0, 0 );
+            goto uiZ;
+        }
+        normExpSig = softfloat_normSubnormalBF16Sig( frac );
+        exp = normExpSig.exp - 1;
+        frac = normExpSig.sig;
+    }
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    uiZ = packToF32UI( sign, exp, (uint_fast32_t) frac<<16 );
+ uiZ:
+    uZ.ui = uiZ;
     return uZ.f;
 
 }
 
+
+
diff --git a/source/include/internals.h b/source/include/internals.h
index ea14a7d..5e6d4bd 100644
--- a/source/include/internals.h
+++ b/source/include/internals.h
@@ -103,13 +103,14 @@ float16_t
 /*----------------------------------------------------------------------------
 *----------------------------------------------------------------------------*/
 #define signBF16UI( a ) ((bool) ((uint16_t) (a)>>15))
-#define expBF16UI( a ) ((int_fast8_t) ((a)>>7) & 0xFF)
+#define expBF16UI( a ) ((int_fast16_t) ((a)>>7) & 0xFF)
 #define fracBF16UI( a ) ((a) & 0x07F)
 #define packToBF16UI( sign, exp, sig ) (((uint16_t) (sign)<<15) + ((uint16_t) (exp)<<7) + (sig))
 
 #define isNaNBF16UI( a ) (((~(a) & 0x7FC0) == 0) && ((a) & 0x07F))
 
 bfloat16_t softfloat_roundPackToBF16( bool, int_fast16_t, uint_fast16_t );
+struct exp8_sig16 softfloat_normSubnormalBF16Sig( uint_fast16_t );
 
 /*----------------------------------------------------------------------------
 *----------------------------------------------------------------------------*/
-- 
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