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/* pdp11_fp.c: PDP-11 floating point simulator (32b version)
Copyright (c) 1993-2015, Robert M Supnik
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of Robert M Supnik shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from Robert M Supnik.
24-Mar-15 RMS MMR1 does not track register changes (Johnny Billquist)
20-Apr-13 RMS MMR1 does not track PC changes (Johnny Billquist)
22-Sep-05 RMS Fixed declarations (Sterling Garwood)
04-Oct-04 RMS Added FIS instructions
19-Jan-03 RMS Changed mode definitions for Apple Dev Kit conflict
08-Oct-02 RMS Fixed macro definitions
05-Jun-98 RMS Fixed implementation specific shift bugs
20-Apr-98 RMS Fixed bug in MODf integer truncation
17-Apr-98 RMS Fixed bug in STCfi range check
16-Apr-98 RMS Fixed bugs in STEXP, STCfi, round/pack
09-Apr-98 RMS Fixed bug in LDEXP
04-Apr-98 RMS Fixed bug in MODf condition codes
This module simulates the PDP-11 floating point unit (FP11 series).
It is called from the instruction decoder for opcodes 170000:177777.
The floating point unit recognizes three instruction formats:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ no operand
| 1 1 1 1| 0 0 0 0 0 0| opcode | 170000:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 170077
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ one operand
| 1 1 1 1| 0 0 0| opcode | dest spec | 170100:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 170777
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ register + operand
| 1 1 1 1| opcode | fac | dest spec | 171000:
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 177777
The instruction space is further extended through use of the floating
point status register (FPS) mode bits. Three mode bits affect how
instructions are interpreted:
FPS_D if 0, floating registers are single precision
if 1, floating registers are double precision
FPS_L if 0, integer operands are word
if 1, integer operands are longword
FPS_T if 0, floating operations are rounded
if 1, floating operations are truncated
FPS also contains the condition codes for the floating point unit,
and exception enable bits for individual error conditions. Exceptions
cause a trap through 0244, unless the individual exception, or all
exceptions, are disabled. Illegal address mode, undefined variable,
and divide by zero NOP the current instruction; all other exceptions
permit the instruction to complete.
Floating point specifiers are similar to integer specifiers, with
the length of the operand being up to 8 bytes. In two specific cases,
the floating point unit reads or writes only two bytes, rather than
the length specified by the operand type:
register for integers, only 16b are accessed; if the
operand is 32b, these are the high order 16b
of the operand
immediate for integers or floating point, only 16b are
accessed; if the operand is 32b or 64b, these
are the high order 16b of the operand.
The FP11 cannot update MMR1 on specifier changes, because the
quantity field is too narrow for +8 or -8. Instead, the simulator
records changes to be made and only commits them at instruction
completion. Instructions that can overwrite a general register
(STFPS, STST, STEXP, STCFi in mode 0) need not check for conflicts;
in mode 0, no general register changes occur in the specifier flow.
*/
#include "pdp11_defs.h"
/* Floating point status register */
#define FPS_ER (1u << FPS_V_ER) /* error */
#define FPS_ID (1u << FPS_V_ID) /* interrupt disable */
#define FPS_IUV (1u << FPS_V_IUV) /* int on undef var */
#define FPS_IU (1u << FPS_V_IU) /* int on underflow */
#define FPS_IV (1u << FPS_V_IV) /* int on overflow */
#define FPS_IC (1u << FPS_V_IC) /* int on conv error */
#define FPS_D (1u << FPS_V_D) /* single/double */
#define FPS_L (1u << FPS_V_L) /* word/long */
#define FPS_T (1u << FPS_V_T) /* round/truncate */
#define FPS_N (1u << FPS_V_N)
#define FPS_Z (1u << FPS_V_Z)
#define FPS_V (1u << FPS_V_V)
#define FPS_C (1u << FPS_V_C)
#define FPS_CC (FPS_N + FPS_Z + FPS_V + FPS_C)
#define FPS_RW (FPS_ER + FPS_ID + FPS_IUV + FPS_IU + FPS_IV + \
FPS_IC + FPS_D + FPS_L + FPS_T + FPS_CC)
/* Floating point exception codes */
#define FEC_OP 2 /* illegal op/mode */
#define FEC_DZRO 4 /* divide by zero */
#define FEC_ICVT 6 /* conversion error */
#define FEC_OVFLO 8 /* overflow */
#define FEC_UNFLO 10 /* underflow */
#define FEC_UNDFV 12 /* undef variable */
/* Floating point format, all assignments 32b relative */
#define FP_V_SIGN (63 - 32) /* high lw: sign */
#define FP_V_EXP (55 - 32) /* exponent */
#define FP_V_HB FP_V_EXP /* hidden bit */
#define FP_V_F0 (48 - 32) /* fraction 0 */
#define FP_V_F1 (32 - 32) /* fraction 1 */
#define FP_V_FROUND (31 - 32) /* f round point */
#define FP_V_F2 16 /* low lw: fraction 2 */
#define FP_V_F3 0 /* fraction 3 */
#define FP_V_DROUND (-1) /* d round point */
#define FP_M_EXP 0377
#define FP_SIGN (1u << FP_V_SIGN)
#define FP_EXP (FP_M_EXP << FP_V_EXP)
#define FP_HB (1u << FP_V_HB)
#define FP_FRACH ((1u << FP_V_HB) - 1)
#define FP_FRACL 0xFFFFFFFF
#define FP_BIAS 0200 /* exponent bias */
#define FP_GUARD 3 /* guard bits */
/* Data lengths */
#define WORD 2
#define LONG 4
#define QUAD 8
/* Reg change word */
#define FPCHG(v,r) (((v) << FPCHG_V_VAL) | (r))
#define FPCHG_REG 07 /* register number */
#define FPCHG_V_VAL 3 /* offset to value */
#define FPCHG_GETREG(x) ((x) & FPCHG_REG)
#define FPCHG_GETVAL(x) ((x) >> FPCHG_V_VAL)
/* Double precision operations on 64b quantities */
#define F_LOAD(qd,ac,ds) \
ds.h = ac.h; ds.l = (qd)? ac.l: 0
#define F_LOAD_P(qd,ac,ds) \
ds->h = ac.h; ds->l = (qd)? ac.l: 0
#define F_LOAD_FRAC(qd,ac,ds) \
ds.h = (ac.h & FP_FRACH) | FP_HB; \
ds.l = (qd)? ac.l: 0
#define F_STORE(qd,sr,ac) \
ac.h = sr.h; if ((qd)) ac.l = sr.l
#define F_STORE_P(qd,sr,ac) \
ac.h = sr->h; if ((qd)) ac.l = sr->l
#define F_GET_FRAC_P(sr,ds) \
ds.l = sr->l; \
ds.h = (sr->h & FP_FRACH) | FP_HB
#define F_ADD(s2,s1,ds) \
ds.l = (s1.l + s2.l) & 0xFFFFFFFF; \
ds.h = (s1.h + s2.h + (ds.l < s2.l)) & 0xFFFFFFFF
#define F_SUB(s2,s1,ds) \
ds.h = (s1.h - s2.h - (s1.l < s2.l)) & 0xFFFFFFFF; \
ds.l = (s1.l - s2.l) & 0xFFFFFFFF
#define F_LT(x,y) ((x.h < y.h) || ((x.h == y.h) && (x.l < y.l)))
#define F_LT_AP(x,y) (((x->h & ~FP_SIGN) < (y->h & ~FP_SIGN)) || \
(((x->h & ~FP_SIGN) == (y->h & ~FP_SIGN)) && (x->l < y->l)))
#define F_LSH_V(sr,n,ds) \
ds.h = (((n) >= 32)? (sr.l << ((n) - 32)): \
(sr.h << (n)) | ((sr.l >> (32 - (n))) & and_mask[n])) \
& 0xFFFFFFFF; \
ds.l = ((n) >= 32)? 0: (sr.l << (n)) & 0xFFFFFFFF
#define F_RSH_V(sr,n,ds) \
ds.l = (((n) >= 32)? (sr.h >> ((n) - 32)) & and_mask[64 - (n)]: \
((sr.l >> (n)) & and_mask[32 - (n)]) | \
(sr.h << (32 - (n)))) & 0xFFFFFFFF; \
ds.h = ((n) >= 32)? 0: \
((sr.h >> (n)) & and_mask[32 - (n)]) & 0xFFFFFFFF
/* For the constant shift macro, arguments must in the range [2,31] */
#define F_LSH_1(ds) ds.h = ((ds.h << 1) | ((ds.l >> 31) & 1)) & 0xFFFFFFFF; \
ds.l = (ds.l << 1) & 0xFFFFFFFF
#define F_RSH_1(ds) ds.l = ((ds.l >> 1) & 0x7FFFFFFF) | ((ds.h & 1) << 31); \
ds.h = ((ds.h >> 1) & 0x7FFFFFFF)
#define F_LSH_K(sr,n,ds) \
ds.h = ((sr.h << (n)) | ((sr.l >> (32 - (n))) & and_mask[n])) \
& 0xFFFFFFFF; \
ds.l = (sr.l << (n)) & 0xFFFFFFFF
#define F_RSH_K(sr,n,ds) \
ds.l = (((sr.l >> (n)) & and_mask[32 - (n)]) | \
(sr.h << (32 - (n)))) & 0xFFFFFFFF; \
ds.h = ((sr.h >> (n)) & and_mask[32 - (n)]) & 0xFFFFFFFF
#define F_LSH_GUARD(ds) F_LSH_K(ds,FP_GUARD,ds)
#define F_RSH_GUARD(ds) F_RSH_K(ds,FP_GUARD,ds)
#define GET_BIT(ir,n) (((ir) >> (n)) & 1)
#define GET_SIGN(ir) GET_BIT((ir), FP_V_SIGN)
#define GET_EXP(ir) (((ir) >> FP_V_EXP) & FP_M_EXP)
#define GET_SIGN_L(ir) GET_BIT((ir), 31)
#define GET_SIGN_W(ir) GET_BIT((ir), 15)
extern jmp_buf save_env;
extern uint32 cpu_type;
extern int32 FEC, FEA, FPS;
extern int32 CPUERR, trap_req;
extern int32 N, Z, V, C;
extern int32 R[8];
extern int32 STKLIM;
extern int32 cm, isenable, dsenable, MMR0, MMR1;
extern fpac_t FR[6];
fpac_t zero_fac = { 0, 0 };
fpac_t one_fac = { 1, 0 };
fpac_t fround_fac = { (1u << (FP_V_FROUND + 32)), 0 };
fpac_t fround_guard_fac = { 0, (1u << (FP_V_FROUND + FP_GUARD)) };
fpac_t dround_guard_fac = { (1u << (FP_V_DROUND + FP_GUARD)), 0 };
fpac_t fmask_fac = { 0xFFFFFFFF, (1u << (FP_V_HB + FP_GUARD + 1)) - 1 };
static const uint32 and_mask[33] = { 0,
0x1, 0x3, 0x7, 0xF,
0x1F, 0x3F, 0x7F, 0xFF,
0x1FF, 0x3FF, 0x7FF, 0xFFF,
0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF,
0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF,
0x1FFFFF, 0x3FFFFF, 0x7FFFFF, 0xFFFFFF,
0x1FFFFFF, 0x3FFFFFF, 0x7FFFFFF, 0xFFFFFFF,
0x1FFFFFFF, 0x3FFFFFFF, 0x7FFFFFFF, 0xFFFFFFFF
};
int32 backup_PC;
int32 fp_change;
int32 fpnotrap (int32 code);
int32 GeteaFW (int32 spec);
int32 GeteaFP (int32 spec, int32 len);
uint32 ReadI (int32 addr, int32 spec, int32 len);
t_bool ReadFP (fpac_t *fac, int32 addr, int32 spec, int32 len);
void WriteI (int32 data, int32 addr, int32 spec, int32 len);
void WriteFP (fpac_t *data, int32 addr, int32 spec, int32 len);
int32 setfcc (int32 old_status, int32 result_high, int32 newV);
int32 addfp11 (fpac_t *src1, fpac_t *src2);
int32 mulfp11 (fpac_t *src1, fpac_t *src2);
int32 divfp11 (fpac_t *src1, fpac_t *src2);
int32 modfp11 (fpac_t *src1, fpac_t *src2, fpac_t *frac);
void frac_mulfp11 (fpac_t *src1, fpac_t *src2);
int32 roundfp11 (fpac_t *src);
int32 round_and_pack (fpac_t *fac, int32 exp, fpac_t *frac, int r);
extern int32 ReadW (int32 addr);
extern void WriteW (int32 data, int32 addr);
extern void set_stack_trap (int32 adr);
/* Set up for instruction decode and execution */
void fp11 (int32 IR)
{
int32 dst, ea, ac, dstspec;
int32 i, qdouble, lenf, leni;
int32 newV, exp, sign;
fpac_t fac, fsrc, modfrac;
static const uint32 i_limit[2][2] = {
{ 0x80000000, 0x80010000 },
{ 0x80000000, 0x80000001 }
};
backup_PC = PC; /* save PC for FEA */
fp_change = 0; /* assume no reg chg */
ac = (IR >> 6) & 03; /* fac is IR<7:6> */
dstspec = IR & 077;
qdouble = FPS & FPS_D;
lenf = qdouble? QUAD: LONG;
switch ((IR >> 8) & 017) { /* decode IR<11:8> */
case 000:
switch (ac) { /* decode IR<7:6> */
case 0: /* specials */
if (IR == 0170000) { /* CFCC */
N = (FPS >> PSW_V_N) & 1;
Z = (FPS >> PSW_V_Z) & 1;
V = (FPS >> PSW_V_V) & 1;
C = (FPS >> PSW_V_C) & 1;
}
else if (IR == 0170001) /* SETF */
FPS = FPS & ~FPS_D;
else if (IR == 0170002) /* SETI */
FPS = FPS & ~FPS_L;
else if (IR == 0170011) /* SETD */
FPS = FPS | FPS_D;
else if (IR == 0170012) /* SETL */
FPS = FPS | FPS_L;
else fpnotrap (FEC_OP);
break;
case 1: /* LDFPS */
dst = (dstspec <= 07)? R[dstspec]: ReadW (GeteaFW (dstspec));
FPS = dst & FPS_RW;
break;
case 2: /* STFPS */
FPS = FPS & FPS_RW;
if (dstspec <= 07)
R[dstspec] = FPS;
else WriteW (FPS, GeteaFW (dstspec));
break;
case 3: /* STST */
if (dstspec <= 07)
R[dstspec] = FEC;
else WriteI ((FEC << 16) | FEA, GeteaFP (dstspec, LONG),
dstspec, LONG);
break;
} /* end switch <7:6> */
break; /* end case 0 */
case 001:
switch (ac) { /* decode IR<7:6> */
case 0: /* CLRf */
WriteFP (&zero_fac, GeteaFP (dstspec, lenf), dstspec, lenf);
FPS = (FPS & ~FPS_CC) | FPS_Z;
break;
case 1: /* TSTf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf))
FPS = setfcc (FPS, fsrc.h, 0);
break;
case 2: /* ABSf */
if (ReadFP (&fsrc, ea = GeteaFP (dstspec, lenf), dstspec, lenf)) {
if (GET_EXP (fsrc.h) == 0)
fsrc = zero_fac;
else fsrc.h = fsrc.h & ~FP_SIGN;
WriteFP (&fsrc, ea, dstspec, lenf);
FPS = setfcc (FPS, fsrc.h, 0);
}
break;
case 3: /* NEGf */
if (ReadFP (&fsrc, ea = GeteaFP (dstspec, lenf), dstspec, lenf)) {
if (GET_EXP (fsrc.h) == 0)
fsrc = zero_fac;
else fsrc.h = fsrc.h ^ FP_SIGN;
WriteFP (&fsrc, ea, dstspec, lenf);
FPS = setfcc (FPS, fsrc.h, 0);
}
break;
} /* end switch <7:6> */
break; /* end case 1 */
case 005: /* LDf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_STORE (qdouble, fsrc, FR[ac]);
FPS = setfcc (FPS, fsrc.h, 0);
}
break;
case 010: /* STf */
F_LOAD (qdouble, FR[ac], fac);
WriteFP (&fac, GeteaFP (dstspec, lenf), dstspec, lenf);
break;
case 017: /* LDCff' */
if (ReadFP (&fsrc, GeteaFP (dstspec, 12 - lenf), dstspec, 12 - lenf)) {
if (GET_EXP (fsrc.h) == 0)
fsrc = zero_fac;
if ((FPS & (FPS_D + FPS_T)) == 0)
newV = roundfp11 (&fsrc);
else newV = 0;
F_STORE (qdouble, fsrc, FR[ac]);
FPS = setfcc (FPS, fsrc.h, newV);
}
break;
case 014: /* STCff' */
F_LOAD (qdouble, FR[ac], fac);
if (GET_EXP (fac.h) == 0)
fac = zero_fac;
if ((FPS & (FPS_D + FPS_T)) == FPS_D)
newV = roundfp11 (&fac);
else newV = 0;
WriteFP (&fac, GeteaFP (dstspec, 12 - lenf), dstspec, 12 - lenf);
FPS = setfcc (FPS, fac.h, newV);
break;
case 007: /* CMPf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
if (GET_EXP (fsrc.h) == 0)
fsrc = zero_fac;
if (GET_EXP (fac.h) == 0)
fac = zero_fac;
if ((fsrc.h == fac.h) && (fsrc.l == fac.l)) { /* equal? */
FPS = (FPS & ~FPS_CC) | FPS_Z;
if ((fsrc.h | fsrc.l) == 0) { /* zero? */
F_STORE (qdouble, zero_fac, FR[ac]);
}
}
else { /* unequal */
FPS = (FPS & ~FPS_CC) | ((fsrc.h >> (FP_V_SIGN - PSW_V_N)) & FPS_N);
if ((GET_SIGN (fsrc.h ^ fac.h) == 0) && (fac.h != 0) &&
F_LT (fsrc, fac))
FPS = FPS ^ FPS_N;
}
}
break;
case 015: /* LDEXP */
dst = (dstspec <= 07)? R[dstspec]: ReadW (GeteaFW (dstspec));
F_LOAD (qdouble, FR[ac], fac);
fac.h = (fac.h & ~FP_EXP) | (((dst + FP_BIAS) & FP_M_EXP) << FP_V_EXP);
newV = 0;
if ((dst > 0177) && (dst <= 0177600)) {
if (dst < 0100000) {
if (fpnotrap (FEC_OVFLO))
fac = zero_fac;
newV = FPS_V;
}
else {
if (fpnotrap (FEC_UNFLO))
fac = zero_fac;
}
}
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, newV);
break;
case 012: /* STEXP */
dst = (GET_EXP (FR[ac].h) - FP_BIAS) & 0177777;
N = GET_SIGN_W (dst);
Z = (dst == 0);
V = 0;
C = 0;
FPS = (FPS & ~FPS_CC) | (N << PSW_V_N) | (Z << PSW_V_Z);
if (dstspec <= 07)
R[dstspec] = dst;
else WriteW (dst, GeteaFW (dstspec));
break;
case 016: /* LDCif */
leni = FPS & FPS_L? LONG: WORD;
if (dstspec <= 07)
fac.l = R[dstspec] << 16;
else fac.l = ReadI (GeteaFP (dstspec, leni), dstspec, leni);
fac.h = 0;
if (fac.l) {
if ((sign = GET_SIGN_L (fac.l)))
fac.l = (fac.l ^ 0xFFFFFFFF) + 1;
for (i = 0; GET_SIGN_L (fac.l) == 0; i++)
fac.l = fac.l << 1;
exp = ((FPS & FPS_L)? FP_BIAS + 32: FP_BIAS + 16) - i;
fac.h = (sign << FP_V_SIGN) | (exp << FP_V_EXP) |
((fac.l >> (31 - FP_V_HB)) & FP_FRACH);
fac.l = (fac.l << (FP_V_HB + 1)) & FP_FRACL;
if ((FPS & (FPS_D + FPS_T)) == 0)
roundfp11 (&fac);
}
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, 0);
break;
case 013: /* STCfi */
sign = GET_SIGN (FR[ac].h); /* get sign, */
exp = GET_EXP (FR[ac].h); /* exponent, */
F_LOAD_FRAC (qdouble, FR[ac], fac); /* fraction */
if (FPS & FPS_L) {
leni = LONG;
i = FP_BIAS + 32;
}
else {
leni = WORD;
i = FP_BIAS + 16;
}
C = 0;
if (exp <= FP_BIAS)
dst = 0;
else if (exp > i) {
dst = 0;
C = 1;
}
else {
F_RSH_V (fac, FP_V_HB + 1 + i - exp, fsrc);
if (leni == WORD)
fsrc.l = fsrc.l & ~0177777;
if (fsrc.l >= i_limit[leni == LONG][sign]) {
dst = 0;
C = 1;
}
else {
dst = fsrc.l;
if (sign)
dst = -dst;
}
}
N = GET_SIGN_L (dst);
Z = (dst == 0);
V = 0;
if (C)
fpnotrap (FEC_ICVT);
FPS = (FPS & ~FPS_CC) | (N << PSW_V_N) |
(Z << PSW_V_Z) | (C << PSW_V_C);
if (dstspec <= 07)
R[dstspec] = (dst >> 16) & 0177777;
else WriteI (dst, GeteaFP (dstspec, leni), dstspec, leni);
break;
case 002: /* MULf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
newV = mulfp11 (&fac, &fsrc);
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, newV);
}
break;
case 003: /* MODf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
newV = modfp11 (&fac, &fsrc, &modfrac);
F_STORE (qdouble, fac, FR[ac | 1]);
F_STORE (qdouble, modfrac, FR[ac]);
FPS = setfcc (FPS, modfrac.h, newV);
}
break;
case 004: /* ADDf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
newV = addfp11 (&fac, &fsrc);
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, newV);
}
break;
case 006: /* SUBf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
if (GET_EXP (fsrc.h) != 0)
fsrc.h = fsrc.h ^ FP_SIGN;
newV = addfp11 (&fac, &fsrc);
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, newV);
}
break;
case 011: /* DIVf */
if (ReadFP (&fsrc, GeteaFP (dstspec, lenf), dstspec, lenf)) {
F_LOAD (qdouble, FR[ac], fac);
if (GET_EXP (fsrc.h) == 0) /* divide by zero? */
fpnotrap (FEC_DZRO);
else { /* no, do divide */
newV = divfp11 (&fac, &fsrc);
F_STORE (qdouble, fac, FR[ac]);
FPS = setfcc (FPS, fac.h, newV);
}
}
break;
} /* end switch fop */
/* Now process any general register modification */
if (fp_change != 0) {
int32 reg = FPCHG_GETREG (fp_change); /* get register */
int32 val = FPCHG_GETVAL (fp_change); /* get value */
if (val & 020) /* negative? */
val = val | (-16); /* ensure proper sext */
R[reg] = (R[reg] + val) & 0177777; /* commit change */
}
return;
}
/* Effective address calculation for word integers */
int32 GeteaFW (int32 spec)
{
int32 adr, reg, ds;
reg = spec & 07; /* register number */
ds = (reg == 7)? isenable: dsenable; /* dspace if not PC */
switch (spec >> 3) { /* decode spec<5:3> */
default: /* can't get here */
case 1: /* (R) */
return (R[reg] | ds);
case 2: /* (R)+ */
adr = R[reg]; /* post increment */
if (reg == 7) /* commit PC chg now */
R[reg] = (R[reg] + 2) & 0177777;
else fp_change = FPCHG (2, reg); /* others, update later */
return (adr | ds);
case 3: /* @(R)+ */
adr = R[reg]; /* post increment */
if (reg == 7) /* commit PC chg now */
R[reg] = (R[reg] + 2) & 0177777;
else fp_change = FPCHG (2, reg); /* others, update later */
adr = ReadW (adr | ds);
return (adr | dsenable);
case 4: /* -(R) */
adr = (R[reg] - 2) & 0177777; /* predecrement */
if (reg == 7) /* commit PC chg now */
R[reg] = adr;
else fp_change = FPCHG (-2, reg); /* others, update later */
if ((reg == 6) && (cm == MD_KER) && (adr < (STKLIM + STKL_Y)))
set_stack_trap (adr);
return (adr | ds);
case 5: /* @-(R) */
adr = (R[reg] - 2) & 0177777; /* predecrement */
if (reg == 7) /* commit PC chg now */
R[reg] = adr;
else fp_change = FPCHG (-2, reg); /* others, update later */
if ((reg == 6) && (cm == MD_KER) && (adr < (STKLIM + STKL_Y)))
set_stack_trap (adr);
adr = ReadW (adr | ds);
return (adr | dsenable);
case 6: /* d(r) */
adr = ReadW (PC | isenable);
PC = (PC + 2) & 0177777;
return (((R[reg] + adr) & 0177777) | dsenable);
case 7: /* @d(R) */
adr = ReadW (PC | isenable);
PC = (PC + 2) & 0177777;
adr = ReadW (((R[reg] + adr) & 0177777) | dsenable);
return (adr | dsenable);
} /* end switch */
}
/* Effective address calculation for fp operands
Inputs:
spec = specifier
len = length
Outputs:
VA = virtual address
Warnings:
- Do not call this routine for integer mode 0 operands
- Do not call this routine more than once per instruction
Note that for modes 06 and 07, it is OKAY to bail out of the FP
instruction immediately; no general register updates can occur.
*/
int32 GeteaFP (int32 spec, int32 len)
{
int32 adr, reg, ds;
reg = spec & 07; /* reg number */
ds = (reg == 7)? isenable: dsenable; /* dspace if not PC */
switch (spec >> 3) { /* case on spec */
case 0: /* floating AC */
if (reg >= 06) {
fpnotrap (FEC_OP);
ABORT (TRAP_INT); /* scuttle instr */
}
return 0;
case 1: /* (R) */
return (R[reg] | ds);
case 2: /* (R)+ */
adr = R[reg]; /* post increment */
if (reg == 7) /* commit PC chg now */
R[reg] = (R[reg] + 2) & 0177777;
else fp_change = FPCHG (len, reg); /* others, update later */
return (adr | ds);
case 3: /* @(R)+ */
adr = R[reg]; /* post increment */
if (reg == 7) /* commit PC chg now */
R[reg] = (R[reg] + 2) & 0177777;
else fp_change = FPCHG (2, reg); /* others, update later */
adr = ReadW (adr | ds);
return (adr | dsenable);
case 4: /* -(R) */
adr = (R[reg] - len) & 0177777; /* predecrement */
if (reg == 7) /* commit PC chg now */
R[reg] = adr;
else fp_change = FPCHG (-len, reg); /* others, udpate later */
if ((reg == 6) && (cm == MD_KER) && (adr < (STKLIM + STKL_Y)))
set_stack_trap (adr);
return (adr | ds);
case 5: /* @-(R) */
adr = (R[reg] - 2) & 0177777; /* predecrement */
if (reg == 7) /* commit PC chg now */
R[reg] = adr;
else fp_change = FPCHG (-2, reg); /* others, update later */
if ((reg == 6) && (cm == MD_KER) && ((adr - 2) < (STKLIM + STKL_Y)))
set_stack_trap (adr);
adr = ReadW (adr | ds);
return (adr | dsenable);
case 6: /* d(r) */
adr = ReadW (PC | isenable);
PC = (PC + 2) & 0177777;
return (((R[reg] + adr) & 0177777) | dsenable);
case 7: /* @d(R) */
adr = ReadW (PC | isenable);
PC = (PC + 2) & 0177777;
adr = ReadW (((R[reg] + adr) & 0177777) | dsenable);
return (adr | dsenable);
} /* end switch */
return 0;
}
/* Read integer operand
Inputs:
VA = virtual address, VA<18:16> = mode, I/D space
spec = specifier
len = length (2/4 bytes)
Outputs:
data = data read from memory or I/O space
*/
uint32 ReadI (int32 VA, int32 spec, int32 len)
{
if ((len == WORD) || (spec == 027))
return (ReadW (VA) << 16);
return ((ReadW (VA) << 16) |
ReadW ((VA & ~0177777) | ((VA + 2) & 0177777)));
}
/* Read floating operand
Inputs:
fptr = pointer to output
VA = virtual address, VA<18:16> = mode, I/D space
spec = specifier
len = length (4/8 bytes)
Output:
TRUE if read succeeded
FALSE if instruction must be NOP'd
*/
t_bool ReadFP (fpac_t *fptr, int32 VA, int32 spec, int32 len)
{
int32 exta;
if (spec <= 07) {
F_LOAD_P (len == QUAD, FR[spec], fptr);
return TRUE;
}
if (spec == 027) {
fptr->h = (ReadW (VA) << FP_V_F0);
fptr->l = 0;
}
else {
exta = VA & ~0177777;
fptr->h = (ReadW (VA) << FP_V_F0) |
(ReadW (exta | ((VA + 2) & 0177777)) << FP_V_F1);
if (len == QUAD) fptr->l =
(ReadW (exta | ((VA + 4) & 0177777)) << FP_V_F2) |
(ReadW (exta | ((VA + 6) & 0177777)) << FP_V_F3);
else fptr->l = 0;
}
if ((GET_SIGN (fptr->h) != 0) &&
(GET_EXP (fptr->h) == 0) &&
(fpnotrap (FEC_UNDFV) == 0))
return FALSE;
return TRUE;
}
/* Write integer result
Inputs:
data = data to be written
VA = virtual address, VA<18:16> = mode, I/D space
spec = specifier
len = length
Outputs: none
*/
void WriteI (int32 data, int32 VA, int32 spec, int32 len)
{
WriteW ((data >> 16) & 0177777, VA);
if ((len == WORD) || (spec == 027))
return;
WriteW (data & 0177777, (VA & ~0177777) | ((VA + 2) & 0177777));
return;
}
/* Write floating result
Inputs:
fptr = pointer to data to be written
VA = virtual address, VA<18:16> = mode, I/D space
spec = specifier
len = length
Outputs: none
*/
void WriteFP (fpac_t *fptr, int32 VA, int32 spec, int32 len)
{
int32 exta;
if (spec <= 07) {
F_STORE_P (len == QUAD, fptr, FR[spec]);
return;
}
WriteW ((fptr->h >> FP_V_F0) & 0177777, VA);
if (spec == 027)
return;
exta = VA & ~0177777;
WriteW ((fptr->h >> FP_V_F1) & 0177777, exta | ((VA + 2) & 0177777));
if (len == LONG)
return;
WriteW ((fptr->l >> FP_V_F2) & 0177777, exta | ((VA + 4) & 0177777));
WriteW ((fptr->l >> FP_V_F3) & 0177777, exta | ((VA + 6) & 0177777));
return;
}
/* FIS instructions */
t_stat fis11 (int32 IR)
{
int32 reg, exta;
fpac_t fac, fsrc;
reg = IR & 07; /* isolate reg */
if (reg == 7) /* choose I,D */
exta = isenable;
else exta = dsenable;
if (IR & 000740) { /* defined? */
if (CPUT (CPUT_03)) /* 11/03 reads word */
ReadW (exta | R[reg]);
ABORT (TRAP_ILL);
}
FEC = 0; /* no errors */
FPS = FPS_IU|FPS_IV; /* trap ovf,unf */
fsrc.h = (ReadW (exta | R[reg]) << FP_V_F0) |
(ReadW (exta | ((R[reg] + 2) & 0177777)) << FP_V_F1);
fsrc.l = 0;
fac.h = (ReadW (exta | ((R[reg] + 4) & 0177777)) << FP_V_F0) |
(ReadW (exta | ((R[reg] + 6) & 0177777)) << FP_V_F1);
fac.l = 0;
if (GET_SIGN (fsrc.h) && (GET_EXP (fsrc.h) == 0)) /* clean 0's */
fsrc.h = fsrc.l = 0;
if (GET_SIGN (fac.h) && (GET_EXP (fac.l) == 0))
fac.h = fac.l = 0;
N = Z = V = C = 0; /* clear cc's */
switch ((IR >> 3) & 3) { /* case IR<5:3> */
case 0: /* FAD */
addfp11 (&fac, &fsrc);
break;
case 1: /* FSUB */
if (fsrc.h != 0) /* invert sign */
fsrc.h = fsrc.h ^ FP_SIGN;
addfp11 (&fac, &fsrc);
break;
case 2: /* FMUL */
mulfp11 (&fac, &fsrc);
break;
case 3: /* FDIV */
if (fsrc.h == 0) { /* div by 0? */
V = N = C = 1; /* set cc's */
setTRAP (TRAP_FPE); /* set trap */
return SCPE_OK;
}
else divfp11 (&fac, &fsrc);
break;
}
if (FEC == 0) { /* no err? */
WriteW ((fac.h >> FP_V_F0) & 0177777, exta | ((R[reg] + 4) & 0177777));
WriteW ((fac.h >> FP_V_F1) & 0177777, exta | ((R[reg] + 6) & 0177777));
R[reg] = (R[reg] + 4) & 0177777; /* pop stack */
N = (GET_SIGN (fac.h) != 0); /* set N,Z */
Z = (fac.h == 0);
}
else if (FEC == FEC_OVFLO) /* ovf? trap set */
V = 1;
else if (FEC == FEC_UNFLO) /* unf? trap set */
V = N = 1;
else return SCPE_IERR; /* what??? */
return SCPE_OK;
}
/* Floating point add
Inputs:
facp = pointer to src1 (output)
fsrcp = pointer to src2
Outputs:
ovflo = overflow variable
*/
int32 addfp11 (fpac_t *facp, fpac_t *fsrcp)
{
int32 facexp, fsrcexp, ediff;
fpac_t facfrac, fsrcfrac;
if (F_LT_AP (facp, fsrcp)) { /* if !fac! < !fsrc! */
facfrac = *facp;
*facp = *fsrcp; /* swap operands */
*fsrcp = facfrac;
}
facexp = GET_EXP (facp->h); /* get exponents */
fsrcexp = GET_EXP (fsrcp->h);
if (facexp == 0) { /* fac = 0? */
*facp = fsrcexp? *fsrcp: zero_fac; /* result fsrc or 0 */
return 0;
}
if (fsrcexp == 0) /* fsrc = 0? no op */
return 0;
ediff = facexp - fsrcexp; /* exponent diff */
if (ediff >= 60) /* too big? no op */
return 0;
F_GET_FRAC_P (facp, facfrac); /* get fractions */
F_GET_FRAC_P (fsrcp, fsrcfrac);
F_LSH_GUARD (facfrac); /* guard fractions */
F_LSH_GUARD (fsrcfrac);
if (GET_SIGN (facp->h) != GET_SIGN (fsrcp->h)) { /* signs different? */
if (ediff) { /* sub, shf fsrc */
F_RSH_V (fsrcfrac, ediff, fsrcfrac);
}
F_SUB (fsrcfrac, facfrac, facfrac); /* sub fsrc from fac */
if ((facfrac.h | facfrac.l) == 0) { /* result zero? */
*facp = zero_fac; /* no overflow */
return 0;
}
if (ediff <= 1) { /* big normalize? */
if ((facfrac.h & (0x00FFFFFF << FP_GUARD)) == 0) {
F_LSH_K (facfrac, 24, facfrac);
facexp = facexp - 24;
}
if ((facfrac.h & (0x00FFF000 << FP_GUARD)) == 0) {
F_LSH_K (facfrac, 12, facfrac);
facexp = facexp - 12;
}
if ((facfrac.h & (0x00FC0000 << FP_GUARD)) == 0) {
F_LSH_K (facfrac, 6, facfrac);
facexp = facexp - 6;
}
}
while (GET_BIT (facfrac.h, FP_V_HB + FP_GUARD) == 0) {
F_LSH_1 (facfrac);
facexp = facexp - 1;
}
}
else {
if (ediff) {
F_RSH_V (fsrcfrac, ediff, fsrcfrac); /* add, shf fsrc */
}
F_ADD (fsrcfrac, facfrac, facfrac); /* add fsrc to fac */
if (GET_BIT (facfrac.h, FP_V_HB + FP_GUARD + 1)) {
F_RSH_1 (facfrac); /* carry out, shift */
facexp = facexp + 1;
}
}
return round_and_pack (facp, facexp, &facfrac, 1);
}
/* Floating point multiply
Inputs:
facp = pointer to src1 (output)
fsrcp = pointer to src2
Outputs:
ovflo = overflow indicator
*/
int32 mulfp11 (fpac_t *facp, fpac_t *fsrcp)
{
int32 facexp, fsrcexp;
fpac_t facfrac, fsrcfrac;
facexp = GET_EXP (facp->h); /* get exponents */
fsrcexp = GET_EXP (fsrcp->h);
if ((facexp == 0) || (fsrcexp == 0)) { /* test for zero */
*facp = zero_fac;
return 0;
}
F_GET_FRAC_P (facp, facfrac); /* get fractions */
F_GET_FRAC_P (fsrcp, fsrcfrac);
facexp = facexp + fsrcexp - FP_BIAS; /* calculate exp */
facp->h = facp->h ^ fsrcp->h; /* calculate sign */
frac_mulfp11 (&facfrac, &fsrcfrac); /* multiply fracs */
/* Multiplying two numbers in the range [.5,1) produces a result in the
range [.25,1). Therefore, at most one bit of normalization is required
to bring the result back to the range [.5,1).
*/
if (GET_BIT (facfrac.h, FP_V_HB + FP_GUARD) == 0) {
F_LSH_1 (facfrac);
facexp = facexp - 1;
}
return round_and_pack (facp, facexp, &facfrac, 1);
}
/* Floating point mod
Inputs:
facp = pointer to src1 (integer result)
fsrcp = pointer to src2
fracp = pointer to fractional result
Outputs:
ovflo = overflow indicator
See notes on multiply for initial operation
*/
int32 modfp11 (fpac_t *facp, fpac_t *fsrcp, fpac_t *fracp)
{
int32 facexp, fsrcexp;
fpac_t facfrac, fsrcfrac, fmask;
facexp = GET_EXP (facp->h); /* get exponents */
fsrcexp = GET_EXP (fsrcp->h);
if ((facexp == 0) || (fsrcexp == 0)) { /* test for zero */
*fracp = zero_fac;
*facp = zero_fac;
return 0;
}
F_GET_FRAC_P (facp, facfrac); /* get fractions */
F_GET_FRAC_P (fsrcp, fsrcfrac);
facexp = facexp + fsrcexp - FP_BIAS; /* calculate exp */
fracp->h = facp->h = facp->h ^ fsrcp->h; /* calculate sign */
frac_mulfp11 (&facfrac, &fsrcfrac); /* multiply fracs */
/* Multiplying two numbers in the range [.5,1) produces a result in the
range [.25,1). Therefore, at most one bit of normalization is required
to bring the result back to the range [.5,1).
*/
if (GET_BIT (facfrac.h, FP_V_HB + FP_GUARD) == 0) {
F_LSH_1 (facfrac);
facexp = facexp - 1;
}
/* There are three major cases of MODf:
1. Exp <= FP_BIAS (all fraction). Return 0 as integer, product as
fraction. Underflow can occur.
2. Exp > FP_BIAS + #fraction bits (all integer). Return product as
integer, 0 as fraction. Overflow can occur.
3. FP_BIAS < exp <= FP_BIAS + #fraction bits. Separate integer and
fraction and return both. Neither overflow nor underflow can occur.
*/
if (facexp <= FP_BIAS) { /* case 1 */
*facp = zero_fac;
return round_and_pack (fracp, facexp, &facfrac, 1);
}
if (facexp > ((FPS & FPS_D)? FP_BIAS + 56: FP_BIAS + 24)) {
*fracp = zero_fac; /* case 2 */
return round_and_pack (facp, facexp, &facfrac, 0);
}
F_RSH_V (fmask_fac, facexp - FP_BIAS, fmask); /* shift mask */
fsrcfrac.l = facfrac.l & fmask.l; /* extract fraction */
fsrcfrac.h = facfrac.h & fmask.h;
if ((fsrcfrac.h | fsrcfrac.l) == 0)
*fracp = zero_fac;
else {
F_LSH_V (fsrcfrac, facexp - FP_BIAS, fsrcfrac);
fsrcexp = FP_BIAS;
if ((fsrcfrac.h & (0x00FFFFFF << FP_GUARD)) == 0) {
F_LSH_K (fsrcfrac, 24, fsrcfrac);
fsrcexp = fsrcexp - 24;
}
if ((fsrcfrac.h & (0x00FFF000 << FP_GUARD)) == 0) {
F_LSH_K (fsrcfrac, 12, fsrcfrac);
fsrcexp = fsrcexp - 12;
}
if ((fsrcfrac.h & (0x00FC0000 << FP_GUARD)) == 0) {
F_LSH_K (fsrcfrac, 6, fsrcfrac);
fsrcexp = fsrcexp - 6;
}
while (GET_BIT (fsrcfrac.h, FP_V_HB + FP_GUARD) == 0) {
F_LSH_1 (fsrcfrac);
fsrcexp = fsrcexp - 1;
}
round_and_pack (fracp, fsrcexp, &fsrcfrac, 1);
}
facfrac.l = facfrac.l & ~fmask.l;
facfrac.h = facfrac.h & ~fmask.h;
return round_and_pack (facp, facexp, &facfrac, 0);
}
/* Fraction multiply
Inputs:
f1p = pointer to multiplier (output)
f2p = pointer to multiplicand fraction
Note: the inputs are unguarded; the output is guarded.
This routine performs a classic shift-and-add multiply. The low
order bit of the multiplier is tested; if 1, the multiplicand is
added into the high part of the double precision result. The
result and the multiplier are both shifted right 1.
For the 24b x 24b case, this routine develops 48b of result.
For the 56b x 56b case, this routine only develops the top 64b
of the the result. Because the inputs are normalized fractions,
the interesting part of the result is the high 56+guard bits.
Everything shifted off to the right, beyond 64b, plays no part
in rounding or the result.
There are many possible optimizations in this routine: scanning
for groups of zeroes, particularly in the 56b x 56b case; using
"extended multiply" capability if available in the hardware.
*/
void frac_mulfp11 (fpac_t *f1p, fpac_t *f2p)
{
fpac_t result, mpy, mpc;
int32 i;
result = zero_fac; /* clear result */
mpy = *f1p; /* get operands */
mpc = *f2p;
F_LSH_GUARD (mpc); /* guard multipicand */
if ((mpy.l | mpc.l) == 0) { /* 24b x 24b? */
for (i = 0; i < 24; i++) {
if (mpy.h & 1)
result.h = result.h + mpc.h;
F_RSH_1 (result);
mpy.h = mpy.h >> 1;
}
}
else {
if (mpy.l != 0) { /* 24b x 56b? */
for (i = 0; i < 32; i++) {
if (mpy.l & 1) {
F_ADD (mpc, result, result);
}
F_RSH_1 (result);
mpy.l = mpy.l >> 1;
}
}
for (i = 0; i < 24; i++) {
if (mpy.h & 1) {
F_ADD (mpc, result, result);
}
F_RSH_1 (result);
mpy.h = mpy.h >> 1;
}
}
*f1p = result;
return;
}
/* Floating point divide
Inputs:
facp = pointer to dividend (output)
fsrcp = pointer to divisor
Outputs:
ovflo = overflow indicator
Source operand must be checked for zero by caller!
*/
int32 divfp11 (fpac_t *facp, fpac_t *fsrcp)
{
int32 facexp, fsrcexp, i, count, qd;
fpac_t facfrac, fsrcfrac, quo;
fsrcexp = GET_EXP (fsrcp->h); /* get divisor exp */
facexp = GET_EXP (facp->h); /* get dividend exp */
if (facexp == 0) { /* test for zero */
*facp = zero_fac; /* result zero */
return 0;
}
F_GET_FRAC_P (facp, facfrac); /* get fractions */
F_GET_FRAC_P (fsrcp, fsrcfrac);
F_LSH_GUARD (facfrac); /* guard fractions */
F_LSH_GUARD (fsrcfrac);
facexp = facexp - fsrcexp + FP_BIAS + 1; /* calculate exp */
facp->h = facp->h ^ fsrcp->h; /* calculate sign */
qd = FPS & FPS_D;
count = FP_V_HB + FP_GUARD + (qd? 33: 1); /* count = 56b/24b */
quo = zero_fac;
for (i = count; (i > 0) && ((facfrac.h | facfrac.l) != 0); i--) {
F_LSH_1 (quo); /* shift quotient */
if (!F_LT (facfrac, fsrcfrac)) { /* divd >= divr? */
F_SUB (fsrcfrac, facfrac, facfrac); /* divd - divr */
if (qd) /* double or single? */
quo.l = quo.l | 1;
else quo.h = quo.h | 1;
}
F_LSH_1 (facfrac); /* shift divd */
}
if (i > 0) { /* early exit? */
F_LSH_V (quo, i, quo);
}
/* Dividing two numbers in the range [.5,1) produces a result in the
range [.5,2). Therefore, at most one bit of normalization is required
to bring the result back to the range [.5,1). The choice of counts
and quotient bit positions makes this work correctly.
*/
if (GET_BIT (quo.h, FP_V_HB + FP_GUARD) == 0) {
F_LSH_1 (quo);
facexp = facexp - 1;
}
return round_and_pack (facp, facexp, &quo, 1);
}
/* Update floating condition codes
Note that FC is only set by STCfi via the integer condition codes
Inputs:
oldst = current status
result = high result
newV = new V
Outputs:
newst = new status
*/
int32 setfcc (int32 oldst, int32 result, int32 newV)
{
oldst = (oldst & ~FPS_CC) | newV;
if (GET_SIGN (result))
oldst = oldst | FPS_N;
if (GET_EXP (result) == 0)
oldst = oldst | FPS_Z;
return oldst;
}
/* Round (in place) floating point number to f_floating
Inputs:
fptr = pointer to floating number
Outputs:
ovflow = overflow
*/
int32 roundfp11 (fpac_t *fptr)
{
fpac_t outf;
outf = *fptr; /* get argument */
F_ADD (fround_fac, outf, outf); /* round */
if (GET_SIGN (outf.h ^ fptr->h)) { /* flipped sign? */
outf.h = (outf.h ^ FP_SIGN) & 0xFFFFFFFF; /* restore sign */
if (fpnotrap (FEC_OVFLO)) /* if no int, clear */
*fptr = zero_fac;
else *fptr = outf; /* return rounded */
return FPS_V; /* overflow */
}
*fptr = outf; /* round was ok */
return 0; /* no overflow */
}
/* Round result of calculation, test overflow, pack
Input:
facp = pointer to result, sign in place
exp = result exponent, right justified
fracp = pointer to result fraction, right justified with
guard bits
r = round (1) or truncate (0)
Outputs:
ovflo = overflow indicator
*/
int32 round_and_pack (fpac_t *facp, int32 exp, fpac_t *fracp, int r)
{
fpac_t frac;
frac = *fracp; /* get fraction */
if (r && ((FPS & FPS_T) == 0)) {
if (FPS & FPS_D) {
F_ADD (dround_guard_fac, frac, frac);
}
else {
F_ADD (fround_guard_fac, frac, frac);
}
if (GET_BIT (frac.h, FP_V_HB + FP_GUARD + 1)) {
F_RSH_1 (frac);
exp = exp + 1;
}
}
F_RSH_GUARD (frac);
facp->l = frac.l & FP_FRACL;
facp->h = (facp->h & FP_SIGN) | ((exp & FP_M_EXP) << FP_V_EXP) |
(frac.h & FP_FRACH);
if (exp > 0377) {
if (fpnotrap (FEC_OVFLO))
*facp = zero_fac;
return FPS_V;
}
if ((exp <= 0) && (fpnotrap (FEC_UNFLO)))
*facp = zero_fac;
return 0;
}
/* Process floating point exception
Inputs:
code = exception code
Outputs:
int = FALSE if interrupt enabled, TRUE if disabled
*/
int32 fpnotrap (int32 code)
{
static const int32 test_code[] = { 0, 0, 0, FPS_IC, FPS_IV, FPS_IU, FPS_IUV };
if ((code >= FEC_ICVT) &&
(code <= FEC_UNDFV) &&
((FPS & test_code[code >> 1]) == 0))
return TRUE;
FPS = FPS | FPS_ER;
FEC = code;
FEA = (backup_PC - 2) & 0177777;
if ((FPS & FPS_ID) == 0)
setTRAP (TRAP_FPE);
return FALSE;
}