[Ffmpeg-cvslog] r5955 - in trunk/libavutil: softfloat.c softfloat.h
michael
subversion
Tue Aug 8 09:58:10 CEST 2006
Author: michael
Date: Tue Aug 8 09:58:10 2006
New Revision: 5955
Added:
trunk/libavutil/softfloat.c
trunk/libavutil/softfloat.h
Log:
floating point "emulation" code
unused currently, but might come in handy for some fpu-less cpus
Added: trunk/libavutil/softfloat.c
==============================================================================
--- (empty file)
+++ trunk/libavutil/softfloat.c Tue Aug 8 09:58:10 2006
@@ -0,0 +1,52 @@
+#include <inttypes.h>
+#include <stdio.h>
+#include <assert.h>
+#include "softfloat.h"
+#include "common.h"
+#include "log.h"
+
+#undef printf
+
+int main(){
+ SoftFloat one= av_int2sf(1, 0);
+ SoftFloat sf1, sf2;
+ double d1, d2;
+ int i, j;
+av_log_level = AV_LOG_DEBUG;
+
+ d1= 1;
+ for(i= 0; i<10; i++){
+ d1= 1/(d1+1);
+ }
+ printf("test1 double=%d\n", (int)(d1 * (1<<24)));
+
+ sf1= one;
+ for(i= 0; i<10; i++){
+ sf1= av_div_sf(one, av_normalize_sf(av_add_sf(one, sf1)));
+ }
+ printf("test1 sf =%d\n", av_sf2int(sf1, 24));
+
+
+ for(i= 0; i<100; i++){
+ START_TIMER
+ d1= i;
+ d2= i/100.0;
+ for(j= 0; j<1000; j++){
+ d1= (d1+1)*d2;
+ }
+ STOP_TIMER("float add mul")
+ }
+ printf("test2 double=%d\n", (int)(d1 * (1<<24)));
+
+ for(i= 0; i<100; i++){
+ START_TIMER
+ sf1= av_int2sf(i, 0);
+ sf2= av_div_sf(av_int2sf(i, 2), av_int2sf(200, 3));
+ for(j= 0; j<1000; j++){
+ sf1= av_mul_sf(av_add_sf(sf1, one),sf2);
+ }
+ STOP_TIMER("softfloat add mul")
+ }
+ printf("test2 sf =%d (%d %d)\n", av_sf2int(sf1, 24), sf1.exp, sf1.mant);
+ return 0;
+}
Added: trunk/libavutil/softfloat.h
==============================================================================
--- (empty file)
+++ trunk/libavutil/softfloat.h Tue Aug 8 09:58:10 2006
@@ -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);
+}
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