ref: 543e6478226a896bfff8e749c53dc41cfc42ed4d
dir: /sys/src/games/v8e/cpufp.c/
#include <u.h>
#include <libc.h>
#include "dat.h"
#include "fns.h"
/* BUGS: Not bit accurate. */
enum {
ADD,
SUB,
MUL,
DIV,
CMP,
};
enum {
EBIAS = 129
};
#define zero(x) (((x) & 0xff80) == 0)
#define inval(x) (((x) & 0xff80) == 0x8000)
#define expo(x) ((x) >> 7 & 0xff)
#define mantf(x) (1<<23 | ((x) & 0x7f) << 16 | (x) >> 16)
#define mantd(x) (1ULL<<55|((x)&0x7f)<<48|((x)&0xffff0000)<<16| \
(x)>>16&0xffff0000|(u16int)((x)>>48))
#define sign(x) ((int)x << 16 >> 30 | 1)
#define makef(s, e, m) ((s)&0x8000|(e)<<7|(m)<<16|(m)>>16&0x7f)
#define maked(s, e, m) (s&0x8000|(e)<<7|(uvlong)(m)<<48|(uvlong)((m)&0xffff0000)<<16| \
(m)>>16&0xffff0000|(m)>>48&0x7f)
static double
vfc(u32int a)
{
union { u32int a; float b; } u;
if(zero(a)) return 0;
a -= 0x100;
u.a = a >> 16 | a << 16;
return u.b;
}
static double
vdc(u64int a)
{
union { u64int a; double b; } u;
if(zero(a)) return 0;
u.a = mantd(a) >> 3 & (1ULL<<52)-1 | expo(a) + 894 << 52 | sign(a) & 1ULL<<63;
return u.b;
}
static int
clz32(u32int a)
{
int n;
static uchar c[16] = {4, 3, 2, 2, 1, 1, 1, 1};
n = 0;
if((a >> 16) == 0){n += 16; a <<= 16;}
if((a >> 24) == 0){n += 8; a <<= 8;}
if((a >> 28) == 0){n += 4; a <<= 4;}
return n + c[a >> 28];
}
static int
clz64(uvlong a)
{
int n;
static uchar c[16] = {4, 3, 2, 2, 1, 1, 1, 1};
n = 0;
if((a >> 32) == 0){n += 32; a <<= 32;}
if((a >> 48) == 0){n += 16; a <<= 16;}
if((a >> 56) == 0){n += 8; a <<= 8;}
if((a >> 60) == 0){n += 4; a <<= 4;}
return n + c[a >> 60];
}
static int
magcmpd(u64int a, u64int b)
{
int e;
s64int m;
e = expo(a) - expo(b);
if(e > 0) return 1;
if(e < 0) return -1;
m = mantd(a) - mantd(b);
if(m > 0) return 1;
if(m < 0) return -1;
return 0;
}
static int
cmpd(u64int a, u64int b)
{
int s;
if(zero(a)){
if(zero(b)) return 0;
return -sign(b);
}
if(zero(b)) return sign(a);
s = sign(a) - sign(b);
if(s > 0) return 1;
if(s < 0) return -1;
return magcmpd(a, b);
}
static u32int
addf(u32int a, u32int b, int sub)
{
int e1, e2, m1, m2, s1, s2;
int n;
u32int c;
if(inval(a) || inval(b)) return 0x8000;
if(zero(b)) return a;
if(sub) b ^= 0x8000;
if(zero(a)) return b;
if(magcmpd(a, b) < 0){
c = a;
a = b;
b = c;
}
e1 = expo(a); m1 = mantf(a); s1 = sign(a);
e2 = expo(b); m2 = mantf(b); s2 = sign(b);
if(e1 - e2 >= 24) return a;
m2 >>= e1 - e2;
if(s1 == s2)
m1 += m2;
else
m1 -= m2;
if(m1 == 0) return 0;
n = 8 - clz32(m1);
e1 += n;
if(n > 0) m1 >>= n;
else m1 <<= -n;
return makef(s1, e1, m1);
}
static u32int
mulf(u32int a, u32int b)
{
int e1, e2, m1, m2, s1, s2, l;
if(zero(a) || zero(b)) return 0;
e1 = expo(a); m1 = mantf(a); s1 = sign(a);
e2 = expo(b); m2 = mantf(b); s2 = sign(b);
s1 ^= s2 & -2;
e1 += e2 - EBIAS;
if(e1 <= 0) return 0;
l = (uvlong)m1 * m2 + (1<<22) >> 23;
if((l & 1<<24) != 0){
l >>= 1;
e1++;
}
if(e1 >= 256) return 0x8000;
return makef(s1, e1, l);
}
static u32int
divf(u32int a, u32int b)
{
int e1, e2, m1, m2, s1, s2;
uvlong l;
if(zero(a)) return 0;
if(zero(b)) return 0x8000;
e1 = expo(a); m1 = mantf(a); s1 = sign(a);
e2 = expo(b); m2 = mantf(b); s2 = sign(b);
s1 ^= s2 & -2;
e1 -= e2 - EBIAS;
l = (uvlong) m1 << 40;
l /= m2;
l >>= 17;
if(l == 0) return 0;
while((l & 1<<23) == 0){
l <<= 1;
e1--;
}
if(e1 <= 0) return 0;
if(e1 >= 256) return 0x8000;
return makef(s1, e1, l);
}
static u64int
addd(u64int a, u64int b, int sub)
{
int e1, e2, s1, s2;
u64int m1, m2;
int n;
u64int c;
if(inval(a) || inval(b)) return 0x8000;
if(zero(b)) return a;
if(sub) b ^= 0x8000;
if(zero(a)) return b;
if(magcmpd(a, b) < 0){
c = a;
a = b;
b = c;
}
e1 = expo(a); m1 = mantd(a); s1 = sign(a);
e2 = expo(b); m2 = mantd(b); s2 = sign(b);
if(e1 - e2 >= 56) return a;
m2 >>= e1 - e2;
if(s1 == s2)
m1 += m2;
else
m1 -= m2;
if(m1 == 0) return 0;
n = 8 - clz64(m1);
e1 += n;
if(n > 0) m1 >>= n;
else m1 <<= -n;
return maked(s1, e1, m1);
}
static u64int
mul55(u64int a, u64int b)
{
u64int l;
l = (uvlong)(u32int)a * (u32int)b >> 32;
l += (a >> 32) * (u32int)b;
l += (u32int)a * (b >> 32);
l = l + (1<<21) >> 22;
l += (a >> 32) * (b >> 32) << 10;
l = l + 1 >> 1;
return l;
}
static u64int
mul62(u64int a, u64int b)
{
u64int l;
l = (uvlong)(u32int)a * (u32int)b >> 32;
l += (a >> 32) * (u32int)b;
l += (u32int)a * (b >> 32);
l = l + (1<<28) >> 29;
l += (a >> 32) * (b >> 32) << 3;
l = l + 1 >> 1;
return l;
}
static u64int
muld(u64int a, u64int b)
{
int e1, e2, s1, s2;
uvlong m1, m2;
uvlong l;
if(zero(a) || zero(b)) return 0;
e1 = expo(a); m1 = mantd(a); s1 = sign(a);
e2 = expo(b); m2 = mantd(b); s2 = sign(b);
s1 ^= s2 & -2;
e1 += e2 - EBIAS;
if(e1 <= 0) return 0;
l = mul55(m1, m2);
if((l & 1ULL<<56) != 0){
l >>= 1;
e1++;
}
if(e1 >= 256) return 0x8000;
return maked(s1, e1, l);
}
static u64int
divd(u64int a, u64int b)
{
int e1, e2, s1, s2;
uvlong m1, m2, l;
if(zero(a)) return 0;
if(zero(b)) return 0x8000;
e1 = expo(a); m1 = mantd(a); s1 = sign(a);
e2 = expo(b); m2 = mantd(b); s2 = sign(b);
s1 ^= s2 & -2;
e1 -= e2 - EBIAS;
l = (1ULL<<63) / (m2 >> 28) << 26;
m2 <<= 7;
l = mul62(l, (1ULL<<63) - mul62(l, m2));
l = mul62(l, (1ULL<<63) - mul62(l, m2));
l = mul62(l, (1ULL<<63) - mul62(l, m2));
l = mul62(l, m1 << 7);
l += 1<<6;
l >>= 7;
if(l == 0) return 0;
while((l & 1ULL<<55) == 0){
l <<= 1;
e1--;
}
if(e1 <= 0) return 0;
if(e1 >= 256) return 0x8000;
return maked(s1, e1, l);
}
void
alufp(int o, int r, int s)
{
u64int a, b, v;
vlong c;
int i;
switch(r){
case 2:
b = readm64(amode(s), s);
c = amode(s);
a = readm64(c, s);
break;
case 3:
b = readm64(amode(s), s);
a = readm64(amode(s), s);
c = amode(s);
break;
default: sysfatal("alufp: r==%d", r);
}
switch(o){
case ADD:
if(s == 0x13) v = addd(a, b, 0);
else v = addf(a, b, 0);
break;
case SUB:
if(s == 0x13) v = addd(a, b, 1);
else v = addf(a, b, 1);
break;
case MUL:
if(s == 0x13) v = muld(a, b);
else v = mulf(a, b);
break;
case DIV:
if(s == 0x13) v = divd(a, b);
else v = divf(a, b);
break;
case CMP:
ps &= ~15;
i = cmpd(b, a);
if(i < 0) ps |= FLAGN;
if(i == 0) ps |= FLAGZ;
return;
default:
sysfatal("alufp: unimplemented op=%d", o);
}
// print("%.8ux %d %20.16g %20.16g %20.16g\n", curpc, o, vdc(a), vdc(b), vdc(v));
ps &= ~15;
if(zero(v)) ps |= FLAGZ;
if((v & 0x8000) != 0) ps |= FLAGN;
writem64(c, v, s);
}
static u64int
itof(s32int i)
{
int n;
u64int l;
l = 0;
if(i < 0){
l |= 0x8000;
i = -i;
}else if(i == 0)
return 0;
n = clz32(i);
l |= maked(0, 160 - n, (uvlong)i << 24 + n);
return l;
}
static s64int
ftoi(u64int l)
{
int s, e;
s = sign(l);
e = expo(l);
l = mantd(l);
if(e >= EBIAS + 64) return 1LL<<63;
if(e < EBIAS) return 0;
l >>= EBIAS + 55 - e;
if(s < 0) return -l;
else return l;
}
void
cvtfp(int s, int t, int r)
{
u64int l;
int si, e;
switch(s){
case 0: l = itof((s8int) readm(amode(0), 0)); break;
case 1: l = itof((s16int) readm(amode(1), 1)); break;
case 2: l = itof(readm(amode(2), 2)); break;
case 0x12: l = readm(amode(2), 2); break;
case 0x13: l = readm64(amode(3), 3); break;
default: sysfatal("cvtfp: s==%d", s);
}
if(r) l = addd(l, maked(sign(l), 128, 0), 0);
if(t < 0x10) l = ftoi(l);
ps &= ~15;
switch(t){
case 0:
if((s64int)l != (s8int)l) ps |= FLAGV;
l = (s8int) l;
break;
case 1:
if((s64int)l != (s16int)l) ps |= FLAGV;
l = (s16int) l;
break;
case 2:
if((s64int)l != (s32int)l) ps |= FLAGV;
l = (s32int) l;
break;
case 0x12:
si = sign(l);
e = expo(l);
l = mantd(l);
l += 1ULL<<31;
if((l & 1ULL<<56) != 0){
l >>= 1;
e++;
}
l = maked(si, e, l);
break;
}
writem64(amode(t), l, t);
if(t >= 0x10){
if(zero(l)) ps |= FLAGZ;
if((l & 0x8000) != 0) ps |= FLAGN;
}else{
if(l == 0) ps |= FLAGZ;
if((s64int)l < 0) ps |= FLAGN;
}
}
void
movefp(int t, int n)
{
u64int x;
x = readm64(amode(t), t);
if(inval(x)) sysfatal("invalid float");
ps &= ~(FLAGN|FLAGZ|FLAGV);
if(zero(x))
ps |= FLAGZ;
else{
if(n) x ^= 0x8000;
if((x & 0x8000) != 0) ps |= FLAGN;
}
writem64(amode(t), x, t);
}
void
emod(int s)
{
u64int a, b, m1, m2, l;
u8int a8;
vlong ai, af;
int e1, e2, s1, s2, n;
a = readm64(amode(s), s);
a8 = readm(amode(0), 0);
b = readm64(amode(s), s);
ai = amode(2);
af = amode(s);
if(zero(a) || zero(b)){
ps = ps & ~15 | FLAGZ;
writem(ai, 0, 2);
writem64(af, 0, s);
return;
}
e1 = expo(a); m1 = mantd(a) << 8 | a8; s1 = sign(a);
e2 = expo(b); m2 = mantd(b); s2 = sign(b);
s1 ^= s2 & -2;
e1 += e2 - EBIAS;
if(e1 <= 0){
ps = ps & ~15 | FLAGZ;
writem(ai, 0, 2);
writem64(af, 0, s);
return;
}
l = (uvlong)(u32int)m1 * (u32int)m2 >> 32;
l += (m1 >> 32) * (u32int)m2;
l += (u32int)m1 * (m2 >> 32);
l = l + (1<<29) >> 30;
l += (m1 >> 32) * (m2 >> 32) << 2;
l = l + 1 >> 1;
while((l & 1ULL<<56) != 0){
l = l + 1 >> 1;
e1++;
}
if(e1 >= 256){
ps |= FLAGV;
return;
}
if(e1 < EBIAS){
writem(ai, 0, 2);
writem64(af, maked(s1, e1, l), s);
if(s1 < 0) ps |= FLAGN;
return;
}
writem(ai, l >> 55+EBIAS-e1, 2);
l &= (1ULL<<55+EBIAS-e1) - 1;
if(l == 0){
writem64(af, 0, s);
ps |= FLAGZ;
return;
}
n = clz64(l)-8;
l <<= n;
e1 -= n;
writem64(af, maked(s1, e1, l), s);
if(s1 < 0) ps |= FLAGN;
}
void
fptest(void)
{
}