From a2fd60437d0c7cf21a9365024efaa764bddaf3ab Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Tue, 8 Aug 2006 07:58:10 +0000
Subject: floating point "emulation" code unused currently, but might come in
 handy for some fpu-less cpus

Originally committed as revision 5955 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavutil/softfloat.h | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 libavutil/softfloat.h

(limited to 'libavutil/softfloat.h')

diff --git a/libavutil/softfloat.h b/libavutil/softfloat.h
new file mode 100644
index 0000000000..6b1831aeba
--- /dev/null
+++ b/libavutil/softfloat.h
@@ -0,0 +1,103 @@
+//copyright Michael Niedermayer 2006 license:LGPL
+
+#define MIN_EXP -126
+#define MAX_EXP  126
+#define ONE_BITS 29
+
+typedef struct SoftFloat{
+    int32_t  exp;
+    int32_t mant;
+}SoftFloat;
+
+static SoftFloat av_normalize_sf(SoftFloat a){
+    if(a.mant){
+#if 1
+        while((a.mant + 0x20000000U)<0x40000000U){
+            a.mant += a.mant;
+            a.exp  -= 1;
+        }
+#else
+        int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));
+        a.exp   -= s;
+        a.mant <<= s;
+#endif
+        if(a.exp < MIN_EXP){
+            a.exp = MIN_EXP;
+            a.mant= 0;
+        }
+    }else{
+        a.exp= MIN_EXP;
+    }
+    return a;
+}
+
+static inline SoftFloat av_normalize1_sf(SoftFloat a){
+#if 1
+    if(a.mant + 0x40000000 < 0){
+        a.exp++;
+        a.mant>>=1;
+    }
+    return a;
+#elif 1
+    int t= a.mant + 0x40000000 < 0;
+    return (SoftFloat){a.exp+t, a.mant>>t};
+#else
+    int t= (a.mant + 0x40000000U)>>31;
+    return (SoftFloat){a.exp+t, a.mant>>t};
+#endif
+}
+
+/**
+ *
+ * @return will not be more denormalized then a+b, so if either input is
+ *         normalized then the output wont be worse then the other input
+ *         if both are normalized then the output will be normalized
+ */
+static inline SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){
+    a.exp += b.exp;
+    a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
+    return av_normalize1_sf(a);
+}
+
+/**
+ *
+ * b has to be normalized and not zero
+ * @return will not be more denormalized then a
+ */
+static SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
+    a.exp -= b.exp+1;
+    a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
+    return av_normalize1_sf(a);
+}
+
+static inline int av_cmp_sf(SoftFloat a, SoftFloat b){
+    int t= a.exp - b.exp;
+    if(t<0) return (a.mant >> (-t)) -  b.mant      ;
+    else    return  a.mant          - (b.mant >> t);
+}
+
+static inline SoftFloat av_add_sf(SoftFloat a, SoftFloat b){
+    int t= a.exp - b.exp;
+    if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});
+    else    return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >>   t )});
+}
+
+static inline SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
+    return av_add_sf(a, (SoftFloat){b.exp, -b.mant});
+}
+
+//FIXME sqrt, log, exp, pow, sin, cos
+
+static inline SoftFloat av_int2sf(int v, int frac_bits){
+    return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});
+}
+
+/**
+ *
+ * rounding is to -inf
+ */
+static inline int av_sf2int(SoftFloat v, int frac_bits){
+    v.exp += frac_bits - ONE_BITS;
+    if(v.exp >= 0) return v.mant <<  v.exp ;
+    else           return v.mant >>(-v.exp);
+}
-- 
cgit v1.2.3