ref: c06f967b07ce0cf3c2e3895ef9b608caa5bbce98
dir: /sys/src/9/bcm/fpiarm.c/
/*
* this doesn't attempt to implement ARM floating-point properties
* that aren't visible in the Inferno environment.
* all arithmetic is done in double precision.
* the FP trap status isn't updated.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "ureg.h"
#include "arm.h"
#include "fpi.h"
/* undef this if correct kernel r13 isn't in Ureg;
* check calculation in fpiarm below
*/
#define REG(ur, x) (*(long*)(((char*)(ur))+roff[(x)]))
#define FR(ufp, x) (*(Internal*)(ufp)->regs[(x)&(Nfpctlregs - 1)])
typedef struct FP2 FP2;
typedef struct FP1 FP1;
struct FP2 {
char* name;
void (*f)(Internal, Internal, Internal*);
};
struct FP1 {
char* name;
void (*f)(Internal*, Internal*);
};
enum {
N = 1<<31,
Z = 1<<30,
C = 1<<29,
V = 1<<28,
REGPC = 15,
};
enum {
fpemudebug = 0,
};
#undef OFR
#define OFR(X) ((ulong)&((Ureg*)0)->X)
static int roff[] = {
OFR(r0), OFR(r1), OFR(r2), OFR(r3),
OFR(r4), OFR(r5), OFR(r6), OFR(r7),
OFR(r8), OFR(r9), OFR(r10), OFR(r11),
OFR(r12), OFR(r13), OFR(r14), OFR(pc),
};
static Internal fpconst[8] = { /* indexed by op&7 (ARM 7500 FPA) */
/* s, e, l, h */
{0, 0x1, 0x00000000, 0x00000000}, /* 0.0 */
{0, 0x3FF, 0x00000000, 0x08000000}, /* 1.0 */
{0, 0x400, 0x00000000, 0x08000000}, /* 2.0 */
{0, 0x400, 0x00000000, 0x0C000000}, /* 3.0 */
{0, 0x401, 0x00000000, 0x08000000}, /* 4.0 */
{0, 0x401, 0x00000000, 0x0A000000}, /* 5.0 */
{0, 0x3FE, 0x00000000, 0x08000000}, /* 0.5 */
{0, 0x402, 0x00000000, 0x0A000000}, /* 10.0 */
};
/*
* arm binary operations
*/
static void
fadd(Internal m, Internal n, Internal *d)
{
(m.s == n.s? fpiadd: fpisub)(&m, &n, d);
}
static void
fsub(Internal m, Internal n, Internal *d)
{
m.s ^= 1;
(m.s == n.s? fpiadd: fpisub)(&m, &n, d);
}
static void
fsubr(Internal m, Internal n, Internal *d)
{
n.s ^= 1;
(n.s == m.s? fpiadd: fpisub)(&n, &m, d);
}
static void
fmul(Internal m, Internal n, Internal *d)
{
fpimul(&m, &n, d);
}
static void
fdiv(Internal m, Internal n, Internal *d)
{
fpidiv(&m, &n, d);
}
static void
fdivr(Internal m, Internal n, Internal *d)
{
fpidiv(&n, &m, d);
}
/*
* arm unary operations
*/
static void
fmov(Internal *m, Internal *d)
{
*d = *m;
}
static void
fmovn(Internal *m, Internal *d)
{
*d = *m;
d->s ^= 1;
}
static void
fabsf(Internal *m, Internal *d)
{
*d = *m;
d->s = 0;
}
static void
frnd(Internal *m, Internal *d)
{
short e;
(m->s? fsub: fadd)(fpconst[6], *m, d);
if(IsWeird(d))
return;
fpiround(d);
e = (d->e - ExpBias) + 1;
if(e <= 0)
SetZero(d);
else if(e > FractBits){
if(e < 2*FractBits)
d->l &= ~((1<<(2*FractBits - e))-1);
}else{
d->l = 0;
if(e < FractBits)
d->h &= ~((1<<(FractBits-e))-1);
}
}
/*
* ARM 7500 FPA opcodes
*/
static FP1 optab1[16] = { /* Fd := OP Fm */
[0] {"MOVF", fmov},
[1] {"NEGF", fmovn},
[2] {"ABSF", fabsf},
[3] {"RNDF", frnd},
[4] {"SQTF", /*fsqt*/0},
/* LOG, LGN, EXP, SIN, COS, TAN, ASN, ACS, ATN all `deprecated' */
/* URD and NRM aren't implemented */
};
static FP2 optab2[16] = { /* Fd := Fn OP Fm */
[0] {"ADDF", fadd},
[1] {"MULF", fmul},
[2] {"SUBF", fsub},
[3] {"RSUBF", fsubr},
[4] {"DIVF", fdiv},
[5] {"RDIVF", fdivr},
/* POW, RPW deprecated */
[8] {"REMF", /*frem*/0},
[9] {"FMF", fmul}, /* fast multiply */
[10] {"FDV", fdiv}, /* fast divide */
[11] {"FRD", fdivr}, /* fast reverse divide */
/* POL deprecated */
};
/*
* ARM VFP opcodes
*/
static FP1 voptab1[32] = { /* Vd := OP Vm */
[0] {"MOVF", fmov},
[1] {"ABSF", fabsf},
[2] {"NEGF", fmovn},
[15] {"CVTF", fmov},
};
static FP2 voptab2[16] = { /* Vd := Vn FOP Fm */
[4] {"MULF", fmul},
[6] {"ADDF", fadd},
[7] {"SUBF", fsub},
[8] {"DIVF", fdiv},
};
static ulong
fcmp(Internal *n, Internal *m)
{
int i;
Internal rm, rn;
if(IsWeird(m) || IsWeird(n)){
/* BUG: should trap if not masked */
return V|C;
}
rn = *n;
rm = *m;
fpiround(&rn);
fpiround(&rm);
i = fpicmp(&rn, &rm);
if(i > 0)
return C;
else if(i == 0)
return C|Z;
else
return N;
}
static void
fld(void (*f)(Internal*, void*), int d, ulong ea, int n, FPsave *ufp)
{
void *mem;
mem = (void*)ea;
(*f)(&FR(ufp, d), mem);
if(fpemudebug)
print("MOV%c #%lux, F%d\n", n==8? 'D': 'F', ea, d);
}
static void
fst(void (*f)(void*, Internal*), ulong ea, int s, int n, FPsave *ufp)
{
Internal tmp;
void *mem;
mem = (void*)ea;
tmp = FR(ufp, s);
if(fpemudebug)
print("MOV%c F%d,#%lux\n", n==8? 'D': 'F', s, ea);
(*f)(mem, &tmp);
}
static int
condok(int cc, int c)
{
switch(c){
case 0: /* Z set */
return cc&Z;
case 1: /* Z clear */
return (cc&Z) == 0;
case 2: /* C set */
return cc&C;
case 3: /* C clear */
return (cc&C) == 0;
case 4: /* N set */
return cc&N;
case 5: /* N clear */
return (cc&N) == 0;
case 6: /* V set */
return cc&V;
case 7: /* V clear */
return (cc&V) == 0;
case 8: /* C set and Z clear */
return cc&C && (cc&Z) == 0;
case 9: /* C clear or Z set */
return (cc&C) == 0 || cc&Z;
case 10: /* N set and V set, or N clear and V clear */
return (~cc&(N|V))==0 || (cc&(N|V)) == 0;
case 11: /* N set and V clear, or N clear and V set */
return (cc&(N|V))==N || (cc&(N|V))==V;
case 12: /* Z clear, and either N set and V set or N clear and V clear */
return (cc&Z) == 0 && ((~cc&(N|V))==0 || (cc&(N|V))==0);
case 13: /* Z set, or N set and V clear or N clear and V set */
return (cc&Z) || (cc&(N|V))==N || (cc&(N|V))==V;
case 14: /* always */
return 1;
case 15: /* never (reserved) */
return 0;
}
return 0; /* not reached */
}
static void
unimp(ulong pc, ulong op)
{
char buf[60];
snprint(buf, sizeof(buf), "sys: fp: pc=%lux unimp fp 0x%.8lux", pc, op);
if(fpemudebug)
print("FPE: %s\n", buf);
error(buf);
/* no return */
}
static void
fpaemu(ulong pc, ulong op, Ureg *ur, FPsave *ufp)
{
int rn, rd, tag, o;
long off;
ulong ea;
Internal tmp, *fm, *fn;
/* note: would update fault status here if we noted numeric exceptions */
/*
* LDF, STF; 10.1.1
*/
if(((op>>25)&7) == 6){
if(op & (1<<22))
unimp(pc, op); /* packed or extended */
rn = (op>>16)&0xF;
off = (op&0xFF)<<2;
if((op & (1<<23)) == 0)
off = -off;
ea = REG(ur, rn);
if(rn == REGPC)
ea += 8;
if(op & (1<<24))
ea += off;
rd = (op>>12)&7;
if(op & (1<<20)){
if(op & (1<<15))
fld(fpid2i, rd, ea, 8, ufp);
else
fld(fpis2i, rd, ea, 4, ufp);
}else{
if(op & (1<<15))
fst(fpii2d, ea, rd, 8, ufp);
else
fst(fpii2s, ea, rd, 4, ufp);
}
if((op & (1<<24)) == 0)
ea += off;
if(op & (1<<21))
REG(ur, rn) = ea;
return;
}
/*
* CPRT/transfer, 10.3
*/
if(op & (1<<4)){
rd = (op>>12) & 0xF;
/*
* compare, 10.3.1
*/
if(rd == 15 && op & (1<<20)){
rn = (op>>16)&7;
fn = &FR(ufp, rn);
if(op & (1<<3)){
fm = &fpconst[op&7];
if(fpemudebug)
tag = 'C';
}else{
fm = &FR(ufp, op&7);
if(fpemudebug)
tag = 'F';
}
switch((op>>21)&7){
default:
unimp(pc, op);
case 4: /* CMF: Fn :: Fm */
case 6: /* CMFE: Fn :: Fm (with exception) */
ur->psr &= ~(N|C|Z|V);
ur->psr |= fcmp(fn, fm);
break;
case 5: /* CNF: Fn :: -Fm */
case 7: /* CNFE: Fn :: -Fm (with exception) */
tmp = *fm;
tmp.s ^= 1;
ur->psr &= ~(N|C|Z|V);
ur->psr |= fcmp(fn, &tmp);
break;
}
if(fpemudebug)
print("CMPF %c%d,F%ld =%#lux\n",
tag, rn, op&7, ur->psr>>28);
return;
}
/*
* other transfer, 10.3
*/
switch((op>>20)&0xF){
default:
unimp(pc, op);
case 0: /* FLT */
rn = (op>>16) & 7;
fpiw2i(&FR(ufp, rn), ®(ur, rd));
if(fpemudebug)
print("MOVW[FD] R%d, F%d\n", rd, rn);
break;
case 1: /* FIX */
if(op & (1<<3))
unimp(pc, op);
rn = op & 7;
tmp = FR(ufp, rn);
fpii2w(®(ur, rd), &tmp);
if(fpemudebug)
print("MOV[FD]W F%d, R%d =%ld\n", rn, rd, REG(ur, rd));
break;
case 2: /* FPSR := Rd */
ufp->status = REG(ur, rd);
if(fpemudebug)
print("MOVW R%d, FPSR\n", rd);
break;
case 3: /* Rd := FPSR */
REG(ur, rd) = ufp->status;
if(fpemudebug)
print("MOVW FPSR, R%d\n", rd);
break;
case 4: /* FPCR := Rd */
ufp->control = REG(ur, rd);
if(fpemudebug)
print("MOVW R%d, FPCR\n", rd);
break;
case 5: /* Rd := FPCR */
REG(ur, rd) = ufp->control;
if(fpemudebug)
print("MOVW FPCR, R%d\n", rd);
break;
}
return;
}
/*
* arithmetic
*/
if(op & (1<<3)){ /* constant */
fm = &fpconst[op&7];
if(fpemudebug)
tag = 'C';
}else{
fm = &FR(ufp, op&7);
if(fpemudebug)
tag = 'F';
}
rd = (op>>12)&7;
o = (op>>20)&0xF;
if(op & (1<<15)){ /* monadic */
FP1 *fp;
fp = &optab1[o];
if(fp->f == nil)
unimp(pc, op);
if(fpemudebug)
print("%s %c%ld,F%d\n", fp->name, tag, op&7, rd);
(*fp->f)(fm, &FR(ufp, rd));
} else {
FP2 *fp;
fp = &optab2[o];
if(fp->f == nil)
unimp(pc, op);
rn = (op>>16)&7;
if(fpemudebug)
print("%s %c%ld,F%d,F%d\n", fp->name, tag, op&7, rn, rd);
(*fp->f)(*fm, FR(ufp, rn), &FR(ufp, rd));
}
}
static void
vfpoptoi(Internal *fm, uchar o2, uchar o4)
{
fm->s = o2>>3;
fm->e = ((o2>>3) | ~(o2 & 4)) - 3 + ExpBias;
fm->l = 0;
fm->h = o4 << (20+NGuardBits);
if(fm->e)
fm->h |= HiddenBit;
else
fm->e++;
}
static void
vfpemu(ulong pc, ulong op, Ureg *ur, FPsave *ufp)
{
int sz, vd, o1, o2, o3, o4, o, tag;
long off;
ulong ea;
Word w;
Internal *fm, fc;
/* note: would update fault status here if we noted numeric exceptions */
sz = op & (1<<8);
o1 = (op>>20) & 0xF;
o2 = (op>>16) & 0xF;
vd = (op>>12) & 0xF;
switch((op>>24) & 0xF){
default:
unimp(pc, op);
case 0xD:
/*
* Extension Register load/store A7.6
*/
off = (op&0xFF)<<2;
if((op & (1<<23)) == 0)
off = -off;
ea = REG(ur, o2) + off;
switch(o1&0x7){ /* D(Bit 22) = 0 (5l) */
default:
unimp(pc, op);
case 0:
if(sz)
fst(fpii2d, ea, vd, sz, ufp);
else
fst(fpii2s, ea, vd, sz, ufp);
break;
case 1:
if(sz)
fld(fpid2i, vd, ea, sz, ufp);
else
fld(fpis2i, vd, ea, sz, ufp);
break;
}
break;
case 0xE:
if(op & (1<<4)){
/*
* Register transfer between Core & Extension A7.8
*/
if(sz) /* C(Bit 8) != 0 */
unimp(pc, op);
switch(o1){
default:
unimp(pc, op);
case 0: /* Fn := Rt */
*((Word*)&FR(ufp, o2)) = REG(ur, vd);
if(fpemudebug)
print("MOVWF R%d, F%d\n", vd, o2);
break;
case 1: /* Rt := Fn */
REG(ur, vd) = *((Word*)&FR(ufp, o2));
if(fpemudebug)
print("MOVFW F%d, R%d =%ld\n", o2, vd, REG(ur, vd));
break;
case 0xE: /* FPSCR := Rt */
ufp->status = REG(ur, vd);
if(fpemudebug)
print("MOVW R%d, FPSCR\n", vd);
break;
case 0xF: /* Rt := FPSCR */
if(vd == 0xF){
ur->psr = ufp->status;
if(fpemudebug)
print("MOVW FPSCR, PSR\n");
}else{
REG(ur, vd) = ufp->status;
if(fpemudebug)
print("MOVW FPSCR, R%d\n", vd);
}
break;
}
}
else{
/*
* VFP data processing instructions A7.5
* Note: As per 5l we ignore (D, N, M) bits
*/
if(fpemudebug)
tag = 'F';
o3 = (op>>6) & 0x3;
o4 = op & 0xF;
fm = &FR(ufp, o4);
if(o1 == 0xB){ /* A7-17 */
if(o3 & 0x1){
switch(o2){
default:
o = (o2<<1) | (o3>>1);
break;
case 0x8: /* CVT int -> float/double */
w = *((Word*)fm);
fpiw2i(&FR(ufp, vd), &w);
if(fpemudebug)
print("CVTW%c F%d, F%d\n", sz?'D':'F', o4, vd);
return;
case 0xD: /* CVT float/double -> int */
fpii2w(&w, fm);
*((Word*)&FR(ufp, vd)) = w;
if(fpemudebug)
print("CVT%cW F%d, F%d\n", sz?'D':'F', o4, vd);
return;
case 0x5: /* CMPF(E) */
fm = &fpconst[0];
if(fpemudebug)
tag = 'C';
case 0x4: /* CMPF(E) */
ufp->status &= ~(N|C|Z|V);
ufp->status |= fcmp(&FR(ufp, vd), fm);
if(fpemudebug)
print("CMPF %c%d,F%d =%#lux\n",
tag, (o2&0x1)? 0: o4, vd, ufp->status>>28);
return;
}
}else{ /* VMOV imm (VFPv3 & v4) (5l doesn't generate) */
vfpoptoi(&fc, o2, o4);
fm = &fc;
o = 0;
if(fpemudebug)
tag = 'C';
}
FP1 *vfp;
vfp = &voptab1[o];
if(vfp->f == nil)
unimp(pc, op);
if(fpemudebug)
print("%s %c%d,F%d\n", vfp->name, tag, o4, vd);
(*vfp->f)(fm, &FR(ufp, vd));
}
else { /* A7-16 */
FP2 *vfp;
o = ((o1&0x3)<<1) | (o1&0x8) | (o3&0x1);
vfp = &voptab2[o];
if(vfp->f == nil)
unimp(pc, op);
if(fpemudebug)
print("%s F%d,F%d,F%d\n", vfp->name, o4, o2, vd);
(*vfp->f)(*fm, FR(ufp, o2), &FR(ufp, vd));
}
}
break;
}
}
/*
* returns the number of FP instructions emulated
*/
int
fpiarm(Ureg *ur)
{
ulong op, o, cp;
FPsave *ufp;
int n;
void (*fpemu)(ulong , ulong , Ureg *, FPsave *);
if(up == nil)
panic("fpiarm not in a process");
ufp = up->fpsave;
/*
* because all the emulated fp state is in the proc structure,
* it need not be saved/restored
*/
switch(up->fpstate){
case FPactive:
case FPinactive:
error("illegal instruction: emulated fpu opcode in VFP mode");
case FPinit:
assert(sizeof(Internal) <= sizeof(ufp->regs[0]));
up->fpstate = FPemu;
ufp->control = 0;
ufp->status = (0x01<<28)|(1<<12); /* sw emulation, alt. C flag */
for(n = 0; n < Nfpctlregs; n++)
FR(ufp, n) = fpconst[0];
}
for(n=0; ;n++){
validaddr(ur->pc, 4, 0);
op = *(ulong*)(ur->pc);
if(fpemudebug)
print("%#lux: %#8.8lux ", ur->pc, op);
o = (op>>24) & 0xF;
cp = (op>>8) & 0xF;
if(ISFPAOP(cp, o))
fpemu = fpaemu;
else if(ISVFPOP(cp, o))
fpemu = vfpemu;
else
break;
if(condok(ur->psr, op>>28))
fpemu(ur->pc, op, ur, ufp);
ur->pc += 4; /* pretend cpu executed the instr */
}
if(fpemudebug)
print("\n");
return n;
}