blob: c9eb907ef3d65d83f2be341575e730375e84bda0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
|
#include <stdbool.h>
#include <stdint.h>
#include "platform.h"
#include "primitives.h"
#include "internals.h"
#include "specialize.h"
#include "softfloat.h"
float32_t f32_sqrt( float32_t a )
{
union ui32_f32 uA;
uint_fast32_t uiA;
bool signA;
int_fast16_t expA;
uint_fast32_t sigA, uiZ;
struct exp16_sig32 normExpSig;
int_fast16_t expZ;
uint_fast32_t sigZ;
uint_fast64_t term, rem;
union ui32_f32 uZ;
uA.f = a;
uiA = uA.ui;
signA = signF32UI( uiA );
expA = expF32UI( uiA );
sigA = fracF32UI( uiA );
if ( expA == 0xFF ) {
if ( sigA ) {
uiZ = softfloat_propagateNaNF32UI( uiA, 0 );
goto uiZ;
}
if ( ! signA ) return a;
goto invalid;
}
if ( signA ) {
if ( ! ( expA | sigA ) ) return a;
goto invalid;
}
if ( ! expA ) {
if ( ! sigA ) return a;
normExpSig = softfloat_normSubnormalF32Sig( sigA );
expA = normExpSig.exp;
sigA = normExpSig.sig;
}
expZ = ( ( expA - 0x7F )>>1 ) + 0x7E;
sigA = ( sigA | 0x00800000 )<<8;
sigZ = softfloat_estimateSqrt32( expA, sigA ) + 2;
if ( ( sigZ & 0x7F ) <= 5 ) {
if ( sigZ < 2 ) {
sigZ = 0x7FFFFFFF;
goto roundPack;
}
sigA >>= expA & 1;
term = (uint_fast64_t) sigZ * sigZ;
rem = ( (uint_fast64_t) sigA<<32 ) - term;
while ( UINT64_C( 0x8000000000000000 ) <= rem ) {
--sigZ;
rem += ( (uint_fast64_t) sigZ<<1 ) | 1;
}
sigZ |= ( rem != 0 );
}
sigZ = softfloat_shortShift32Right1Jam( sigZ );
roundPack:
return softfloat_roundPackToF32( 0, expZ, sigZ );
invalid:
softfloat_raiseFlags( softfloat_flag_invalid );
uiZ = defaultNaNF32UI;
uiZ:
uZ.ui = uiZ;
return uZ.f;
}
|
