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Length: 969 (0x3c9)
Types: TextFile
Notes: UNIX file
Names: »ablt.s«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦2d53db1df⟧ UNIX V7 Filesystem
└─ ⟦this⟧ »hr/src/smgr/ablt.s«
//
// _GETBITS(n) - return the next 'n' bits of source
// Entry: SP+4 = number of bits (<=16)
//
// Used: r1 = return value
// rr4= _sp
// r2 = current source word (_sw).
// r0 = n, i.e., #bits more to get
//
.globl getbits_
getbits_:
dec r15, $4
ld (rr14), r13
ld r13, r15
sub r1,r1 // val = 0;
ld r0, L10001+4(r13)
ld r2,sw_
cp r0,$16
ret gt // if (n > 16) then quit;
jr lt,gt50 // else if ( n != 16 || snm != 15)
cp snb_,$15 // do bottom of loop;
jr ne,gt50
ld r1,sw_ // else return whole word in sw
inc sp_+2,$2
ldl rr4,sp_
ld r4,@rr4
ld sw_,r4
ld r13, (rr14)
inc r15, $4
ret
gtloop:
dec r0,$1 // n--;
rl r2,$1
rlc r1,$1 // val = 2*val + bit16(_sw);
dec snb_,$1 // if ( !_snb-- )
jr pl,gt50
inc sp_+2,$2 // { _sp++;
ldl rr4,sp_
ld r2,@rr4 // _sw = *_sp;
ld snb_,$15 // _snb = 15;
gt50: // }
test r0 //
jr nz,gtloop // if ( n ) then gtloop;
ld sw_,r2 // update _sw
ld r13, (rr14)
inc r15, $4
ret
L10001=SS|4