+
+float swf_GetF16(TAG * t)
+{
+ U16 f1 = swf_GetU16(t);
+ if(!(f1&0x3ff)) return 0.0;
+
+ // IEEE 16 is 1-5-10
+ // IEEE 32 is 1-8-23
+ /* gcc 4.1.2 seems to require a union here. *(float*)u doesn't work */
+ union {
+ U32 u;
+ float f;
+ } f2;
+
+ U16 e = (f1>>10)&0x1f;
+ U16 m = f1&0x3ff;
+ /* find highest bit in mantissa */
+ int h=0;
+ while(!(m&0x400)) {
+ m<<=1;
+ h++;
+ }
+ m&=0x3ff;
+ e -= h;
+ e += 0x6f;
+
+ f2.u = (f1&0x8000)<<16; //sign
+ f2.u |= e<<23; //exponent
+ f2.u |= m<<13; //mantissa
+ return *(float*)&f2;
+}
+
+void swf_SetF16(TAG * t, float f)
+{
+ union {
+ U32 u;
+ float f;
+ } v;
+ v.f = f;
+
+ U16 result = (v.u>>16)&0x8000; //sign
+ int exp = ((v.u>>23)&0xff)-0x7f+0x10;
+ U16 m = (v.u>>13)&0x3ff;
+ //fprintf(stderr, "%f: %04x sign, %d exp, %04x mantissa\n", f, result, exp, m);
+ if(exp<-10) {
+ // underflow (clamp to 0.0)
+ exp = 0;
+ m = 0;
+ } else if(exp<0) {
+ // partial underflow- strip some bits
+ m = (m|0x400)>>-exp;
+ exp = 0;
+ } else if(exp>=32) {
+ exp = 31;
+ m = 0x3ff;
+ fprintf(stderr, "Exponent overflow in FLOAT16 encoding\n");
+ } else {
+ exp++;
+ m = (m>>1)|0x200;
+ }
+ result |= exp<<10;
+ result |= m;
+ swf_SetU16(t, result);
+}
+
+float F16toFloat(U16 x)
+{
+ TAG t;
+ t.data = (void*)&x;
+ t.readBit = 0;
+ t.pos = 0;
+ t.len = 2;
+ return swf_GetF16(&t);
+}
+
+float floatToF16(float f)
+{
+ U16 u = 0;
+ TAG t;
+ t.data = (void*)&u;
+ t.len = 0;
+ t.memsize = 2;
+ t.writeBit = 0;
+ swf_SetF16(&t, f);
+ return u;
+}
+