📄 uss_dpopns.s
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divu d2,d6 | Division of shifted remainder movew d6,d4 | Complete 1/B approximation| movel d2,d6 clrw d6 | Create a shifted C in d6 (16 bits) lsrl #1,d6 | Insure no division overflow divu d2,d6 | C/B approximation mulu d7,d6 lsrl #8,d6 | Position correction term lsrl #7,d6 subl d6,d4 lsll #1,d4 | Left shift approximation subxl d6,d6 | Do not overflow orl d6,d4 | 28+ bit 1/B approx in d4, B in d2:d3 swap d2| movel d4,d0 | Save X0 in d0 bsr DPD500 | d4 * d2:d3 -> d2:d3 (in place) negl d3 negxl d2 movel d0,d4 bsr DPD500| asll #1,d3 roxll #1,d2 jcc DPD080 | J/ no shift out moveq #-1,d2 | Set d2:d3 to FFFFFFFF:FFFFFFFF moveq #-1,d3DPD080: |dsw 0| movel sp@+,d4 | Fetch dividend movel sp@+,d5 jra DPM050|| DPD500: Multiply D2:D3 by D4, top 64 bits of result in D2:D3|DPD500: movew d2,d1 mulu d4,d1 | BY partial product swap d2 swap d3 movew d3,d7 movew d2,d6 mulu d4,d7 mulu d4,d6 | AY:CY in d6:d7 movew d6,d7 clrw d6 swap d6 swap d7 | LSR #16,d6:d7 addl d1,d7 clrl d1 addxl d1,d6 | 00:BY + 0A:YC| swap d4 movew d3,d5 movew d2,d1 mulu d4,d5 mulu d4,d1 | AX:CX in d1:d5 addl d5,d7 addxl d1,d6 | AX:CX + 00:BY + 0A:CY| swap d2 swap d3 mulu d4,d3 mulu d4,d2 | BX:DX in d2:d3 movew d2,d3 clrw d2 swap d2 swap d3 | LSR #16,d2:d3 addl d7,d3 addxl d6,d2 | Result in d2:d3| swap d4 | Restore d4 rts#endif| endc ;+++++/*|| page|| DPCMP| =====| Single Precision comparison routine.|| Compare the two arguments provided and set the condition code| register bits N, Z, and V as follows:|| N Z V Relation| = = = ====================================| 1 0 0 X > Y (X is top argument on stack)| 0 1 0 X = Y (within FFUZZ specification)| 0 0 0 X < Y| 0 0 1 X does not compare to Y||||*/| .set DFUZZ,51 | Fifty-one bits of fuzzDPCMP: bsr GETDP2 cmpiw #0x7FF,d0 jne DPC020 | J/ X is not INF or NaN| lsll #1,d2 | Remove implicit bit jeq DPC005 | J/ X is INF|DPC001: |dsw 0 | ** X does not compare to Y ** moveq #CCRV,d0 | CCR V bit movew d0,ccr jmp a0@ | Return|DPC005: cmpiw #0x7FF,d1 jne DPC009 | J/ Y is not INF or NaN| lsll #1,d4 jne DPC001 | J/ Y is NaN (does not compare)| cmpaw a2,a3 jeq DPC001 | /* J/ INF's with same sign - no compare */|DPC009: movew a2,d0 | /* Result based on compl. of X's sign */ eoriw #CCRN,d0 jra DPC011|DPC010: movew a3,d0 | /* Set result based on Y's sign */DPC011: andiw #CCRN,d0 movew d0,ccr jmp a0@||DPC020: cmpiw #0x7FF,d1 jne DPC030 | J/ Y is not NaN or INF| lsll #1,d4 jne DPC001 | J/ Y is NaN - no comparison jra DPC010 | /* Result is based on Y's sign */|DPC030: cmpaw a2,a3 jne DPC010 | /* J/ signs different - use Y's sign */| movew d0,d6 movew d0,d7 | /* Assume X's exp is larger */ subw d1,d6 | Calc difference in exponents jpl DPC031 | J/ positive movew d1,d7 | /* Y's exp is larger */ negw d6DPC031: |dsw 0| lsrw #1,d6 jeq DPC040 | Must subtract to obtain result| subw d0,d1 subxw d0,d0 | Set d0 to sign of Y[exp]-X[exp] movew a2,d1 eorw d1,d0 | Flip if negative values jra DPC011 | Result based on value in d0|DPC040: movew d7,sp@- | Save max exp value, return address movel a0,sp@-| movew a2,d7 notw d7 | Flip sign of opnd (force subtract) moveaw d7,a2| pea DPC041 movel sp@+,a0 | Return address in a0| jra DPXSUB|DPC041: movel sp@+,d0 movel sp@+,d1 moveal sp@,a0 movel d1,sp@ movel d0,sp@- movel a0,sp@- bsr GETDP1 | Fetch and unpack result| movew sp@+,d5 | Recall max exp value| andw d0,d0 jeq DPC050 | J/ zero result| subw d0,d5 cmpiw #DFUZZ,d5 jge DPC050 | J/ within FFUZZ specification - zero| movew a2,d0 | Sign of result into d0 jra DPC011 | Comparison result from sign of sub|DPC050: subw d0,d0 | Force CCR to say "Z" jmp a0@ | Return/*|| page|| GETDP2| ======| Routine called to extract two double precision arguments from| the system stack and place them in the 68000`s registers.|*/GETDP2: moveal sp@+,a1 | /* GETDP2's return address */ moveal sp@+,a0 | Calling routines return address| movel sp@+,d0 | Get TOS (source) operand movel sp@+,d3 | Get low long word subw d2,d2 | Clear carry roxll #1,d0 | Sign bit to bit 0 subxw d2,d2 | Fill d2 with sign bit moveaw d2,a2 | Sign bit info to a2 roll #8,d0 | Left justify mantissa, position exp roll #3,d0 movel d0,d2 | Copy into mantissa register andiw #0x7FF,d0 | Mask to exponent field jeq GETD21 | J/ zero value| eorw d0,d2 | Zero exponent bits in d2 lsrl #1,d2 | Position mantissa bset #31,d2 | Set implicit bit in d2 roll #8,d3 | Position lo long word of mantissa roll #3,d3 eorw d3,d2 | Clever use of EOR to move bits andiw #0xF800,d3 | Trim off bits moved into d2 eorw d3,d2 | Remove noise in d2|GETD21: |dsw 0| movel sp@+,d1 | Get NOS (source) operand movel sp@+,d5 subw d4,d4 | Clear carry roxll #1,d1 | Sign bit carry subxw d4,d4 | Replicate sign bit throughout d4 moveaw d4,a3 | Sign bit info into a3 roll #8,d1 | Left justify mantissa, position exp roll #3,d1 movel d1,d4 | Copy into mantissa register andiw #0x7FF,d1 | Mask to exponent field jeq GETD22 | J/ zero value| eorw d1,d4 | Zero exponent bits in d4 lsrl #1,d4 | Position mantissa bset #31,d4 | Set implicit bit in d4 roll #8,d5 | Position low long word of mantissa roll #3,d5 eorw d5,d4 | Clever use of EOR to move bits andiw #0xF800,d5 | Trim off bits moved into d4 eorw d5,d4 | Remove noise in d4|GETD22: jmp a1@ | Return to caller, its ret addr in a0/*||| page|| GETDP1| ======| Routine called to extract a double precision argument from the| system stack and place it (unpacked) into the 68000's registers.|*/GETDP1: moveal sp@+,a1 | /* Get GETDP1's return address */ moveal sp@+,a0 | Get calling routines return address| movel sp@+,d0 | Get argument movel sp@+,d3 subw d2,d2 | Clear carry roxll #1,d0 | Sign bit into carry subxw d2,d2 | Replicate sign bit throughout d2 moveaw d2,a2 | Sign bit info into a2 roll #8,d0 | Left justify mantissa, position exp roll #3,d0 movel d0,d2 andiw #0x7FF,d0 | Mask to exponent field jeq GETD11 | J/ zero value| eorw d0,d2 | Zero exponent bits in d2 lsrl #1,d2 | Position mantissa bset #31,d2 | Set implicit bit roll #8,d3 | Position lo long word of mantissa roll #3,d3 eorw d3,d2 | Clever use of EOR to move bits andiw #0xF800,d3 | Trim off bits moved to d3 eorw d3,d2 | Remove noise in d2|GETD11: jmp a1@ | Return to caller, its ret addr in a0/*||| page|| DOPRSL| ======| Double precision floating point result (main entry w/ round).| Mantissa in D2:D3, exponent in D0, sign in A2, and return address| in A0. Place a formatted value on the stack.|*/DOPRSL: addl #0x400,d3 | Round the value jcc DOPR01 | J/ no carry out addql #1,d2 jcc DOPR01 | J/ no carry out| roxrl #1,d2 | Adjust mantissa and exponent roxrl #1,d3 addqw #1,d0|DOPR01: andw d0,d0 jle DUNFRS | J/ underflow| cmpiw #0x7FF,d0 | Check for overflow jge DINFRS | J/ overflow| andiw #0xF800,d3 | Trim mantissa eorw d2,d3 | EOR to move over 11 bits andiw #0xF800,d2 | Remove bits moved eorw d2,d3 | Remove noise in d3 subw d1,d1 | Clear carry roxll #1,d2 | Implicit bit into carry addw d0,d2 | Exponent into d2 rorl #8,d2 | Reposition high word rorl #3,d2 movew a2,d0 | Sign bit into carry aslw #1,d0 roxrl #1,d2 rorl #8,d3 rorl #3,d3 movel d3,sp@- | Place value on stack movel d2,sp@-| moveb #0,FPERR | No floating point error jmp a0@ | Return|||DNANRS: moveq #-1,d0 | Set d0 to 0xFFFFFFFF movel d0,sp@- | NaN value movel d0,sp@-| moveb #ERNAN,FPERR moveb #-1,NANFLG jmp a0@||DINFRS: movel a2,d0 | Get sign information movel #0xFFE00000,d1 aslw #1,d0 | Sign bit into carry roxrl #1,d1 clrl sp@- | Low long word = 00000000 movel d1,sp@-| moveb #EROVF,FPERR moveb #-1,INFFLG jmp a0@||DUNFRS: moveb #ERUNF,FPERR moveb #-1,UNFFLG jra DZER01||DZERRS: moveb #0,FPERR||DZER01: clrl sp@- clrl sp@- jmp a0@|| end⌨️ 快捷键说明
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