ack/mach/m68020/as/mach4.c
1994-06-24 14:02:31 +00:00

727 lines
16 KiB
C

/* $Id$ */
/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/*
* Motorola 68020 syntax rules
*/
/* Please do not add more terminal symbols. As it is, 127 terminal symbols
are used, and this is the limit for some "yacc" implementations,
notably the Ultrix one.
*/
operation
: { instrp = instr;
dot_offset = 0;
curr_instr = curr_token;
}
instruction
{ emit_instr();
}
;
instruction
: bcdx DREG ',' DREG
{ emit2($1 | $2 | $4<<9);}
| bcdx '-' '(' AREG ')' ',' '-' '(' AREG ')'
{ emit2($1 | $4 | $9<<9 | 010);}
| ADD sizedef ea_ea
{ add($1, $2);}
| AND sizenon ea_ea
{ and($1, $2);}
| SHIFT sizedef ea_ea
{ shift_op($1, $2);}
| SHIFT sizedef ea /* This syntax is also allowed */
{ checksize($2, 2);
T_EMIT2(($1 & 0177700) | mrg_2,0,0,0);
ea_2(SIZE_W, MEM|ALT);
}
| BR expr
{ branch($1, $2);}
| DBR DREG ',' expr
{ T_EMIT2($1 | $2,0,0,0);
$4.val -= (DOTVAL+dot_offset);
fit(fitw($4.val));
T_EMIT2(loww($4.val), $4.typ,
RELPC|RELO2, relonami);
}
| BITOP ea_ea
{ bitop($1);}
| BITFIELD ea off_width
{ bitfield($1, $3);}
| BF_TO_D ea off_width ',' DREG
{ bitfield($1, $3 | $5<<12);}
| BFINS DREG ',' ea off_width
{ bitfield($1, $5 | $2<<12);}
| DIVMUL sizedef ea ',' DREG
{ checksize($2, 2|4);
if ($2 == SIZE_W) {
T_EMIT2((0140300^($1<<8))|mrg_2|$5<<9,
0, 0, 0);
ea_2(SIZE_W, DTA);
}
else { /* 32 bit dividend or product */
T_EMIT2((046000 | ($1 & ~1)) | mrg_2,
0, 0, 0);
T_EMIT2(($1&1)<<11 | $5<<12 | $5,
0, 0, 0);
ea_2(SIZE_L, DTA);
}
}
| DIVMUL sizedef ea ',' DREG ':' DREG
{ /* 64 bit dividend or product */
checksize($2, 4);
T_EMIT2((046000 | ($1 & ~1)) | mrg_2, 0, 0, 0);
T_EMIT2(($1&1)<<11 | $7<<12 | $5 | 02000 ,0,0,0);
ea_2(SIZE_L, DTA);
}
| DIVL sizedef ea ',' DREG ':' DREG
{ /* 32 bit long division with remainder */
checksize($2, 4);
T_EMIT2(($1 & ~1) | mrg_2, 0, 0, 0);
T_EMIT2(($1 & 1)<<11 | $7<<12 | $5 , 0, 0, 0);
ea_2(SIZE_L, DTA);
}
| LEA ea ',' AREG
{ T_EMIT2(040700 | mrg_2 | $4<<9,0,0,0);
ea_2(SIZE_L, CTR);
}
| op_ea ea
{ if (mrg_2==074)
serror("bad adressing category");
T_EMIT2(($1&0177700) | mrg_2,0,0,0);
ea_2($1&0300, $1&017);
}
| OP_NOOP
{ emit2($1);}
| OP_EXT SIZE DREG
{ checksize($2, ($1 & 0400) ? 4 : (2|4));
emit2($1 | $2+0100 | $3);
}
| OP_RANGE sizedef ea ',' reg
{ T_EMIT2(0300 | ($2<<3) | mrg_2,0,0,0);
T_EMIT2($1 | ($5<<12),0,0,0);
ea_2($2, CTR);
}
| TRAPCC SIZE imm
{ checksize($2, 2|4);
T_EMIT2($1 | ($2>>6)+1,0,0,0);
ea_2($2, 0);
}
| TRAPCC { emit2($1 | 4);}
| PACK '-' '(' AREG ')' ',' '-' '(' AREG ')' ',' imm
{ T_EMIT2($1 | 8 | $4 | $9<<9, 0, 0, 0);
ea_2(SIZE_W, 0);
}
| PACK DREG ',' DREG ',' imm
{ T_EMIT2($1 | $2 | $4<<9, 0, 0, 0);
ea_2(SIZE_W, 0);
}
| CMP sizedef ea_ea
{ cmp($2);}
| CHK sizedef ea ',' DREG
{ checksize($2, 2|4);
T_EMIT2(040000 | mrg_2 | $5<<9 |
($2==SIZE_W ? 0600 : 0400),
0, 0, 0);
ea_2($2, DTA);
}
| MOVE sizenon ea_ea
{ move($2);}
| MOVEM sizedef regs ',' notimmreg
{ movem(0, $2, $3);}
| MOVEM sizedef notimmreg ',' regs
{ movem(1, $2, $5);}
| MOVESP sizedef
{ curr_size = $1; }
ea_ea
{ if ($1 == 0) {
/* movep */
movep($2);
} else if (mrg_1 <= 017) {
T_EMIT2(007000 | $2 | mrg_2,0,0,0);
T_EMIT2(mrg_1 << 12 | 04000,0,0,0);
ea_2($2,ALT|MEM);
} else if (mrg_2 <= 017) {
T_EMIT2(007000 | $2 | mrg_1,0,0,0);
T_EMIT2(mrg_2 << 12,0,0,0);
ea_1($2,ALT|MEM);
} else
badoperand();
}
| MOVEC creg ',' reg
{ T_EMIT2(047172,0,0,0);
T_EMIT2($2 | $4<<12,0,0,0);
}
| MOVEC reg ',' creg
{ T_EMIT2(047173,0,0,0);
T_EMIT2($4 | $2<<12,0,0,0);
}
| EXG reg ',' reg
{ if (($2 & 010) == 0)
emit2(
(0140500|$4|$2<<9)
+
(($4&010)<<3)
);
else
emit2(
(0140610|$2|($4&07)<<9)
-
(($4&010)<<3)
);
}
| SWAP DREG
{ emit2(044100 | $2);}
| OP_IMM imm
{ T_EMIT2($1, 0, 0, 0);
ea_2(SIZE_W, 0);
}
| LINK sizenon AREG ',' imm
{ link_instr($2, $3);}
| UNLK AREG
{ emit2(047130 | $2);}
| TRAP '#' absexp
{ fit(fit4($3));
emit2(047100|low4($3));
}
| BKPT '#' absexp
{ fit(($3 & ~07) == 0);
emit2(044110 | low3($3));
}
| CALLM '#' absexp ',' ea
{ fit(fitb($3));
T_EMIT2(03300 | mrg_2,0,0,0);
T_EMIT2((short) $3,0,0,0);
ea_2(SIZE_L, CTR);
}
| RTM reg
{ emit2(03300 | $2);}
| CAS sizedef DREG ',' DREG ',' ea
{ T_EMIT2(04300 | (($2+0100)<<3) | mrg_2,0,0,0);
T_EMIT2($3 | ($5<<6),0,0,0);
ea_2($2, MEM|ALT);
}
| CAS2 sizedef DREG ':' DREG ',' DREG ':' DREG ','
'(' reg ')' ':' '(' reg ')'
{ checksize($2 , 2|4);
emit2(04374 | (($2+0100)<<3));
emit2($3 | ($7<<6) | ($12<<12));
emit2($5 | ($9<<6) | ($16<<12));
}
| fp_op
| mm_op
;
bcdx : ABCD
| ADDX sizedef
{ $$ = $1 | $2;}
;
creg : CREG
| SPEC { if ($1 != 075)
badoperand();
$$ = 04000;
}
;
off_width /* note: these should be curly brackets, but that would
* leave us without brackets for expressions.
*/
: '[' abs31 ':' abs31 ']'
{ $$ = ($2<<6) | $4;
}
;
abs31 : DREG { $$ = 040 | $1;}
| absexp { fit(fit5($1));
$$ = low5($1);
}
;
op_ea : OP_EA
| SZ_EA sizedef
{ $$ = $1 | $2;}
;
regs : rrange
| regs '/' rrange
{ $$ = $1 | $3;}
;
rrange : reg
{ $$ = 1<<$1;}
| reg '-' reg
{ if ($1 > $3)
badoperand();
for ($$ = 0; $1 <= $3; $1++)
$$ |= (1<<$1);
}
;
ea : DREG
{ mrg_2 = $1;}
| AREG
{ mrg_2 = 010 | $1;}
| SPEC
{ mrg_2 = $1;}
| notimmreg
| imm
;
notimmreg
:
{ mrg_2 = 0; ffew_2 = 0400; /* initialization */}
notimmreg1
;
notimmreg1
: '(' AREG ')'
{ mrg_2 = 020 | $2;}
| '(' AREG ')' '+'
{ mrg_2 = 030 | $2;}
| '-' '(' AREG ')'
{ mrg_2 = 040 | $3;}
| '(' expr ')' sizenon
{ bd_2 = $2; ea7071($4);
RELOMOVE(bd_rel2, relonami);
}
| '(' bd_areg_index ')'
{ if ((mrg_2 & INDEX) == 0)
ffew_2 |= 0100; /* suppress index */
if ( !(mrg_2 & PC_MODE) &&
(ffew_2 & 0300) == 0100 &&
bd_2.typ==S_ABS && fitw(bd_2.val)
)
mrg_2 = (loww(bd_2.val)?050:020) | $2;
else {
mrg_2 = (mrg_2&PC_MODE)?073:(060 | $2);
ffew_2 |= 060; /* long displacement */
}
}
| '(' '[' bd_areg_index ']' index_od ')'
{ switch(mrg_2 & INDEX) {
case 0:
ffew_2 |= 0163; /* suppress index */
break;
case DBL_INDEX:
serror("bad indexing");
case PRE_INDEX:
ffew_2 |= 063; break;
case POST_INDEX:
ffew_2 |= 067; break;
}
mrg_2 = (mrg_2 & PC_MODE) ? 073 : (060 | $3);
}
;
imm : '#' expr
{ mrg_2 = 074; bd_2 = $2;
RELOMOVE(bd_rel2, relonami);
}
;
bd_areg_index
: /* empty */
{ $$ = 0; ffew_2 |= 0200;
/* base-reg suppressed */
bd_2.typ = S_ABS; bd_2.val = (valu_t)0;
/* zero displacement */
}
| expr { $$ = 0; ffew_2 |= 0200;
bd_2 = $1;
RELOMOVE(bd_rel2, relonami);
}
| areg_index
{ bd_2.typ = S_ABS; bd_2.val = (valu_t)0;
}
| expr ',' areg_index
{ $$ = $3; bd_2 = $1;
RELOMOVE(bd_rel2, relonami);
}
;
areg_index
: areg
| index { $$ = 0;
ffew_2 |= 0200; /* base-reg suppressed */
mrg_2 |= PRE_INDEX;
}
| areg ',' index
{ mrg_2 |= PRE_INDEX;
}
;
areg : AREG
| PC { mrg_2 |= PC_MODE;
ffew_2 |= $1; /* base-reg suppressed for zpc */
$$ = 0;
}
;
index : reg sizedef scale
{ checksize($2, 2|4);
ffew_2 |= $1<<12 | ($2&0200)<<4 | $3;
}
;
scale : /* empty */
{ $$ = 0;}
| '*' absexp
{ $$ = checkscale($2);}
;
index_od: /* empty */
{ od_2.typ = S_ABS; od_2.val = (valu_t)0;}
| ',' index
{ od_2.typ = S_ABS; od_2.val = (valu_t)0;
mrg_2 |= POST_INDEX;
}
| ',' expr
{ od_2 = $2;
RELOMOVE(od_rel2, relonami);
}
| ',' index ',' expr
{ od_2 = $4;
mrg_2 |= POST_INDEX;
RELOMOVE(od_rel2, relonami);
}
;
reg : DREG
| AREG
{ $$ = $1 | 010;}
;
sizedef : /* empty */
{ $$ = SIZE_DEF; curr_size = SIZE_DEF; }
| SIZE { curr_size = $1; $$ = $1; }
;
sizenon : /* empty */
{ $$ = SIZE_NON;}
| SIZE
;
ea_ea : ea ','
{ mrg_1 = mrg_2;
bd_1 = bd_2;
od_1 = od_2;
ffew_1 = ffew_2;
RELOMOVE(bd_rel1, bd_rel2);
RELOMOVE(od_rel1, od_rel2);
}
ea
;
fp_op : CP
{ co_id = $1; }
fp_op1
| { co_id = DEF_FP; }
fp_op1
;
fp_op1 : FMOVE fsize ea ',' FPCR
{ check_fsize($2, FSIZE_L);
if ((mrg_2&070) == 010 && $5 != 001)
badoperand();
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0100000|($5<<10)),0,0,0);
ea_2(SIZE_L, 0);
}
| FMOVE fsize FPCR ',' ea
{ check_fsize($2, FSIZE_L);
if ((mrg_2&070) == 010 && $3 == 001)
badoperand();
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0120000|($3<<10)),0,0,0);
ea_2(SIZE_L, ALT);
}
| FMOVE fsize FPREG ',' FPREG
{ emit2(0170000|co_id);
emit2(($3<<10)|($5<<7));
}
| FMOVE fsize ea ',' FPREG
{ ch_sz_dreg($2, mrg_2&070);
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0040000|($2<<10)|($5<<7)),0,0,0);
ea_2(SIZE_L, DTA);
}
| FMOVE fsize FPREG ',' ea
{ ch_sz_dreg($2, mrg_2&070);
if ($2 == FSIZE_P)
serror("packed decimal needs k-factor");
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0060000|($2<<10)|($3<<7)),0,0,0);
ea_2(SIZE_L, DTA|ALT);
}
| FMOVE fsize FPREG ',' ea '{' '#' absexp '}'
{ check_fsize($2, FSIZE_P);
fit(sfit7($8));
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0066000|($3<<7)|low7($8)),0,0,0);
ea_2(SIZE_L, MEM|DTA|ALT);
}
| FMOVE fsize FPREG ',' ea '{' DREG '}'
{ check_fsize($2, FSIZE_P);
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0076000|($3<<7)|($7<<4)),0,0,0);
ea_2(SIZE_L, MEM|DTA|ALT);
}
| FMOVECR fsize '#' absexp ',' FPREG
{ fit(fit7($4));
check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(056000|($6<<7)|low7($4));
}
| FMOVEM FSIZE fregs ',' notimmreg
{ check_fsize($2, FSIZE_X);
if ((mrg_2&070) == 030)
serror("bad addressing category");
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2(0160000 |
(((mrg_2&070)==040 || ($3&04000)) ?
$3 :
(010000|reverse($3,8))),
0,0,0);
ea_2(SIZE_L, MEM|ALT);
}
| FMOVEM FSIZE notimmreg ',' fregs
{ check_fsize($2, FSIZE_X);
if ((mrg_2&070) == 040)
serror("bad addressing category");
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0150000|(($5&04000)?$5:reverse($5,8))),0,0,0);
ea_2(SIZE_L, MEM);
}
| FMOVEM SIZE fcregs ',' ea
{ checksize($2, 4);
if ((mrg_2&070) == 1 && $3!= 02000)
serror("bad addressing category");
if ((mrg_2 & 070) == 0 &&
$3 != 02000 && $3 != 04000 && $3 != 010000)
serror("bad addressing category");
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0120000|$3),0,0,0);
ea_2(SIZE_L, ALT);
}
| FMOVEM SIZE ea ',' fcregs
{ checksize($2, 4);
if ((mrg_2&070) == 1 && $5!= 02000)
serror("bad addressing category");
if ((mrg_2 & 070) == 0 &&
$5 != 02000 && $5 != 04000 && $5 != 010000)
serror("bad addressing category");
T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0100000|$5),0,0,0);
ea_2(SIZE_L, 0);
}
| FDYADIC fsize ea ',' FPREG
{ T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0040000|($2<<10)|($5<<7)|$1),0,0,0);
ch_sz_dreg($2, mrg_2&070);
ea_2(SIZE_L, DTA);
}
| FDYADIC fsize FPREG ',' FPREG
{ check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(($3<<10)|($5<<7)|$1);
}
| FMONADIC fsize ea ',' FPREG
{ T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0040000|($2<<10)|($5<<7)|$1),0,0,0);
ch_sz_dreg($2, mrg_2&070);
ea_2(SIZE_L, DTA);
}
| FMONADIC fsize FPREG ',' FPREG
{ check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(($3<<10)|($5<<7)|$1);
}
| FMONADIC fsize FPREG
{ check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(($3<<10)|($3<<7)|$1);
}
| FSINCOS fsize ea ',' FPREG ':' FPREG
{ T_EMIT2(0170000|co_id|mrg_2,0,0,0);
T_EMIT2(0040000|($2<<10)|($7<<7)|$1|$5,0,0,0);
ea_2(SIZE_L, DTA);
}
| FSINCOS fsize FPREG ',' FPREG ':' FPREG
{ check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(($3<<10)|($7<<7)|$1|$5);
}
| FBCC expr
{ fbranch($1, $2);}
| FDBCC DREG ',' expr
{ T_EMIT2(0170110|co_id|$2,0,0,0);
T_EMIT2($1,0,0,0);
$4.val -= (DOTVAL+dot_offset);
fit(fitw($4.val));
T_EMIT2(loww($4.val), $4.typ,
RELPC|RELO2,relonami);
}
| FNOP
{ emit2(0170200|co_id);
emit2(0);
}
| FSCC ea
{ T_EMIT2(0170100|co_id|mrg_2,0,0,0);
T_EMIT2($1,0,0,0);
ea_2(SIZE_B, DTA|ALT);
}
| FTST fsize ea
{ T_EMIT2((0170000|co_id|mrg_2),0,0,0);
T_EMIT2((0040072|($2<<10)),0,0,0);
ch_sz_dreg($2, mrg_2&070);
ea_2(SIZE_L, DTA);
}
| FTST fsize FPREG
{ check_fsize($2, FSIZE_X);
emit2(0170000|co_id);
emit2(($3<<10)|072);
}
| FSAVRES ea
{ if ((mrg_2&070) == ($1&070))
badoperand();
T_EMIT2((0170000|co_id|($1&0700)|mrg_2),0,0,0);
ea_2(0, $1&07);
}
| FTRAPCC
{ emit2(0170174|co_id);
emit2($1);
}
| FTRAPCC SIZE imm
{ checksize($2, 2|4);
T_EMIT2((0170170|co_id|($2==SIZE_L?03:02)),
0,0,0);
T_EMIT2($1,0,0,0);
ea_2($2,0);
}
;
fregs : DREG
{ $$ = 04000 | $1 << 4; }
| frlist
;
frlist : frrange
| frlist '/' frrange
{ $$ = $1 | $3;}
;
frrange : FPREG
{ $$ = 1 << $1; }
| FPREG '-' FPREG
{ if ($1 > $3)
badoperand();
for ($$ = 0; $1 <= $3; $1++)
$$ |= (1 << $1);
}
;
fcregs : FPCR
{ $$ = $1 << 10; }
| fcregs '/' FPCR
{ $$ = $1 | ($3 << 10); }
;
fsize : /* empty */
{ $$ = FSIZE_X; }
| SIZE
{ if ($1 == SIZE_L)
$$ = FSIZE_L;
else if ($1 == SIZE_W)
$$ = FSIZE_W;
else $$ = FSIZE_B;
}
| FSIZE
;
mm_op : CP
{ co_id = $1; }
mm_op1
| { co_id = DEF_MM; }
mm_op1
;
mm_op1 : /* Coprocessor instructions; syntax may be changed (please).
* No coprocessor defined extension words are emitted.
*/
CPBCC cp_cond expr
{ cpbcc($1 | co_id | $2, $3);
}
| CPDBCC cp_cond DREG ',' expr
{ T_EMIT2($1 | co_id | $3,0,0,0);
$5.val -= (DOTVAL+dot_offset);
fit(fitw($5.val));
T_EMIT2(loww($5.val), $5.typ,
RELPC|RELO2, relonami);
}
| CPGEN
{ T_EMIT2($1 | co_id,0,0,0);
/* NO COMMAND WORD IS EMITTED;
* THIS INSTRUCTIONS IS (STILL) ONE BIG RIDDLE.
* NO EFFECTIVE ADDRESS IS CALCULATED (SYNTAX ?)
*/
}
| CPSAVREST ea
{ T_EMIT2($1 | co_id | mrg_2,0,0,0);
if ($1 & 0100) {
/* restore */
ea_2(SIZE_W, (mrg_2 & 070)==030 ? 0 : CTR);
}
else ea_2(SIZE_W,(mrg_2 & 070)==020 ? 0 : CTR|ALT);
}
| CPSCC cp_cond ea
{ T_EMIT2($1 | co_id | mrg_2,0,0,0);
T_EMIT2($2,0,0,0);
ea_2(SIZE_B,DTA|ALT);
}
| CPTRAPCC cp_cond SIZE imm
{ checksize($3,2|4);
T_EMIT2($1 | co_id | ($3>>6)+1,0,0,0);
T_EMIT2($2,0,0,0);
ea_2($3, 0);
}
| CPTRAPCC cp_cond
{ emit2($1 | co_id | 4);
emit2($2);
}
/* M68030 MMU instructions */
| PFLUSHA
{ emit2(0170000);
emit2($1);
}
| PFLUSH fc ',' mask
{ emit2(0170000);
emit2($1|010000|($4<<5)|$2);
}
| PFLUSH fc ',' mask ',' ea
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|014000|($4<<5)|$2, 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
| PTEST fc ',' ea ',' mask
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|($6<<10)|$2, 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
| PTEST fc ',' ea ',' mask ',' AREG
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|($6<<10)|$2|0400|($8<<5), 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
| PLOAD fc ',' ea
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|$2, 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
| PMOVE MREG ',' ea
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|$2|01000, 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
| PMOVE ea ',' MREG
{ T_EMIT2(0170000|mrg_2, 0, 0, 0);
T_EMIT2($1|$4, 0, 0, 0);
ea_2(SIZE_L, DTA|CTR);
}
;
mask : '#' absexp
{ fit(fit3($2));
$$ = low3($2);
}
;
fc : '#' absexp
{ fit(fit3($2));
$$ = (020|low3($2));
}
| DREG
{ $$ = (010|$1); }
| CREG
{ if ($1 > 1) serror("illegal control register");
$$ = ($1&01);
}
;
cp_cond : DOT absexp
{ fit(fit6($2));
$$ = low6($2);
}
;