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+|
+| bindec.sa 3.4 1/3/91
+|
+| bindec
+|
+| Description:
+| Converts an input in extended precision format
+| to bcd format.
+|
+| Input:
+| a0 points to the input extended precision value
+| value in memory; d0 contains the k-factor sign-extended
+| to 32-bits. The input may be either normalized,
+| unnormalized, or denormalized.
+|
+| Output: result in the FP_SCR1 space on the stack.
+|
+| Saves and Modifies: D2-D7,A2,FP2
+|
+| Algorithm:
+|
+| A1. Set RM and size ext; Set SIGMA = sign of input.
+| The k-factor is saved for use in d7. Clear the
+| BINDEC_FLG for separating normalized/denormalized
+| input. If input is unnormalized or denormalized,
+| normalize it.
+|
+| A2. Set X = abs(input).
+|
+| A3. Compute ILOG.
+| ILOG is the log base 10 of the input value. It is
+| approximated by adding e + 0.f when the original
+| value is viewed as 2^^e * 1.f in extended precision.
+| This value is stored in d6.
+|
+| A4. Clr INEX bit.
+| The operation in A3 above may have set INEX2.
+|
+| A5. Set ICTR = 0;
+| ICTR is a flag used in A13. It must be set before the
+| loop entry A6.
+|
+| A6. Calculate LEN.
+| LEN is the number of digits to be displayed. The
+| k-factor can dictate either the total number of digits,
+| if it is a positive number, or the number of digits
+| after the decimal point which are to be included as
+| significant. See the 68882 manual for examples.
+| If LEN is computed to be greater than 17, set OPERR in
+| USER_FPSR. LEN is stored in d4.
+|
+| A7. Calculate SCALE.
+| SCALE is equal to 10^ISCALE, where ISCALE is the number
+| of decimal places needed to insure LEN integer digits
+| in the output before conversion to bcd. LAMBDA is the
+| sign of ISCALE, used in A9. Fp1 contains
+| 10^^(abs(ISCALE)) using a rounding mode which is a
+| function of the original rounding mode and the signs
+| of ISCALE and X. A table is given in the code.
+|
+| A8. Clr INEX; Force RZ.
+| The operation in A3 above may have set INEX2.
+| RZ mode is forced for the scaling operation to insure
+| only one rounding error. The grs bits are collected in
+| the INEX flag for use in A10.
+|
+| A9. Scale X -> Y.
+| The mantissa is scaled to the desired number of
+| significant digits. The excess digits are collected
+| in INEX2.
+|
+| A10. Or in INEX.
+| If INEX is set, round error occurred. This is
+| compensated for by 'or-ing' in the INEX2 flag to
+| the lsb of Y.
+|
+| A11. Restore original FPCR; set size ext.
+| Perform FINT operation in the user's rounding mode.
+| Keep the size to extended.
+|
+| A12. Calculate YINT = FINT(Y) according to user's rounding
+| mode. The FPSP routine sintd0 is used. The output
+| is in fp0.
+|
+| A13. Check for LEN digits.
+| If the int operation results in more than LEN digits,
+| or less than LEN -1 digits, adjust ILOG and repeat from
+| A6. This test occurs only on the first pass. If the
+| result is exactly 10^LEN, decrement ILOG and divide
+| the mantissa by 10.
+|
+| A14. Convert the mantissa to bcd.
+| The binstr routine is used to convert the LEN digit
+| mantissa to bcd in memory. The input to binstr is
+| to be a fraction; i.e. (mantissa)/10^LEN and adjusted
+| such that the decimal point is to the left of bit 63.
+| The bcd digits are stored in the correct position in
+| the final string area in memory.
+|
+| A15. Convert the exponent to bcd.
+| As in A14 above, the exp is converted to bcd and the
+| digits are stored in the final string.
+| Test the length of the final exponent string. If the
+| length is 4, set operr.
+|
+| A16. Write sign bits to final string.
+|
+| Implementation Notes:
+|
+| The registers are used as follows:
+|
+| d0: scratch; LEN input to binstr
+| d1: scratch
+| d2: upper 32-bits of mantissa for binstr
+| d3: scratch;lower 32-bits of mantissa for binstr
+| d4: LEN
+| d5: LAMBDA/ICTR
+| d6: ILOG
+| d7: k-factor
+| a0: ptr for original operand/final result
+| a1: scratch pointer
+| a2: pointer to FP_X; abs(original value) in ext
+| fp0: scratch
+| fp1: scratch
+| fp2: scratch
+| F_SCR1:
+| F_SCR2:
+| L_SCR1:
+| L_SCR2:
+
+| Copyright (C) Motorola, Inc. 1990
+| All Rights Reserved
+|
+| For details on the license for this file, please see the
+| file, README, in this same directory.
+
+|BINDEC idnt 2,1 | Motorola 040 Floating Point Software Package
+
+#include "fpsp.h"
+
+ |section 8
+
+| Constants in extended precision
+LOG2: .long 0x3FFD0000,0x9A209A84,0xFBCFF798,0x00000000
+LOG2UP1: .long 0x3FFD0000,0x9A209A84,0xFBCFF799,0x00000000
+
+| Constants in single precision
+FONE: .long 0x3F800000,0x00000000,0x00000000,0x00000000
+FTWO: .long 0x40000000,0x00000000,0x00000000,0x00000000
+FTEN: .long 0x41200000,0x00000000,0x00000000,0x00000000
+F4933: .long 0x459A2800,0x00000000,0x00000000,0x00000000
+
+RBDTBL: .byte 0,0,0,0
+ .byte 3,3,2,2
+ .byte 3,2,2,3
+ .byte 2,3,3,2
+
+ |xref binstr
+ |xref sintdo
+ |xref ptenrn,ptenrm,ptenrp
+
+ .global bindec
+ .global sc_mul
+bindec:
+ moveml %d2-%d7/%a2,-(%a7)
+ fmovemx %fp0-%fp2,-(%a7)
+
+| A1. Set RM and size ext. Set SIGMA = sign input;
+| The k-factor is saved for use in d7. Clear BINDEC_FLG for
+| separating normalized/denormalized input. If the input
+| is a denormalized number, set the BINDEC_FLG memory word
+| to signal denorm. If the input is unnormalized, normalize
+| the input and test for denormalized result.
+|
+ fmovel #rm_mode,%FPCR |set RM and ext
+ movel (%a0),L_SCR2(%a6) |save exponent for sign check
+ movel %d0,%d7 |move k-factor to d7
+ clrb BINDEC_FLG(%a6) |clr norm/denorm flag
+ movew STAG(%a6),%d0 |get stag
+ andiw #0xe000,%d0 |isolate stag bits
+ beq A2_str |if zero, input is norm
+|
+| Normalize the denorm
+|
+un_de_norm:
+ movew (%a0),%d0
+ andiw #0x7fff,%d0 |strip sign of normalized exp
+ movel 4(%a0),%d1
+ movel 8(%a0),%d2
+norm_loop:
+ subw #1,%d0
+ lsll #1,%d2
+ roxll #1,%d1
+ tstl %d1
+ bges norm_loop
+|
+| Test if the normalized input is denormalized
+|
+ tstw %d0
+ bgts pos_exp |if greater than zero, it is a norm
+ st BINDEC_FLG(%a6) |set flag for denorm
+pos_exp:
+ andiw #0x7fff,%d0 |strip sign of normalized exp
+ movew %d0,(%a0)
+ movel %d1,4(%a0)
+ movel %d2,8(%a0)
+
+| A2. Set X = abs(input).
+|
+A2_str:
+ movel (%a0),FP_SCR2(%a6) | move input to work space
+ movel 4(%a0),FP_SCR2+4(%a6) | move input to work space
+ movel 8(%a0),FP_SCR2+8(%a6) | move input to work space
+ andil #0x7fffffff,FP_SCR2(%a6) |create abs(X)
+
+| A3. Compute ILOG.
+| ILOG is the log base 10 of the input value. It is approx-
+| imated by adding e + 0.f when the original value is viewed
+| as 2^^e * 1.f in extended precision. This value is stored
+| in d6.
+|
+| Register usage:
+| Input/Output
+| d0: k-factor/exponent
+| d2: x/x
+| d3: x/x
+| d4: x/x
+| d5: x/x
+| d6: x/ILOG
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/final result
+| a1: x/x
+| a2: x/x
+| fp0: x/float(ILOG)
+| fp1: x/x
+| fp2: x/x
+| F_SCR1:x/x
+| F_SCR2:Abs(X)/Abs(X) with $3fff exponent
+| L_SCR1:x/x
+| L_SCR2:first word of X packed/Unchanged
+
+ tstb BINDEC_FLG(%a6) |check for denorm
+ beqs A3_cont |if clr, continue with norm
+ movel #-4933,%d6 |force ILOG = -4933
+ bras A4_str
+A3_cont:
+ movew FP_SCR2(%a6),%d0 |move exp to d0
+ movew #0x3fff,FP_SCR2(%a6) |replace exponent with 0x3fff
+ fmovex FP_SCR2(%a6),%fp0 |now fp0 has 1.f
+ subw #0x3fff,%d0 |strip off bias
+ faddw %d0,%fp0 |add in exp
+ fsubs FONE,%fp0 |subtract off 1.0
+ fbge pos_res |if pos, branch
+ fmulx LOG2UP1,%fp0 |if neg, mul by LOG2UP1
+ fmovel %fp0,%d6 |put ILOG in d6 as a lword
+ bras A4_str |go move out ILOG
+pos_res:
+ fmulx LOG2,%fp0 |if pos, mul by LOG2
+ fmovel %fp0,%d6 |put ILOG in d6 as a lword
+
+
+| A4. Clr INEX bit.
+| The operation in A3 above may have set INEX2.
+
+A4_str:
+ fmovel #0,%FPSR |zero all of fpsr - nothing needed
+
+
+| A5. Set ICTR = 0;
+| ICTR is a flag used in A13. It must be set before the
+| loop entry A6. The lower word of d5 is used for ICTR.
+
+ clrw %d5 |clear ICTR
+
+
+| A6. Calculate LEN.
+| LEN is the number of digits to be displayed. The k-factor
+| can dictate either the total number of digits, if it is
+| a positive number, or the number of digits after the
+| original decimal point which are to be included as
+| significant. See the 68882 manual for examples.
+| If LEN is computed to be greater than 17, set OPERR in
+| USER_FPSR. LEN is stored in d4.
+|
+| Register usage:
+| Input/Output
+| d0: exponent/Unchanged
+| d2: x/x/scratch
+| d3: x/x
+| d4: exc picture/LEN
+| d5: ICTR/Unchanged
+| d6: ILOG/Unchanged
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/final result
+| a1: x/x
+| a2: x/x
+| fp0: float(ILOG)/Unchanged
+| fp1: x/x
+| fp2: x/x
+| F_SCR1:x/x
+| F_SCR2:Abs(X) with $3fff exponent/Unchanged
+| L_SCR1:x/x
+| L_SCR2:first word of X packed/Unchanged
+
+A6_str:
+ tstl %d7 |branch on sign of k
+ bles k_neg |if k <= 0, LEN = ILOG + 1 - k
+ movel %d7,%d4 |if k > 0, LEN = k
+ bras len_ck |skip to LEN check
+k_neg:
+ movel %d6,%d4 |first load ILOG to d4
+ subl %d7,%d4 |subtract off k
+ addql #1,%d4 |add in the 1
+len_ck:
+ tstl %d4 |LEN check: branch on sign of LEN
+ bles LEN_ng |if neg, set LEN = 1
+ cmpl #17,%d4 |test if LEN > 17
+ bles A7_str |if not, forget it
+ movel #17,%d4 |set max LEN = 17
+ tstl %d7 |if negative, never set OPERR
+ bles A7_str |if positive, continue
+ orl #opaop_mask,USER_FPSR(%a6) |set OPERR & AIOP in USER_FPSR
+ bras A7_str |finished here
+LEN_ng:
+ moveql #1,%d4 |min LEN is 1
+
+
+| A7. Calculate SCALE.
+| SCALE is equal to 10^ISCALE, where ISCALE is the number
+| of decimal places needed to insure LEN integer digits
+| in the output before conversion to bcd. LAMBDA is the sign
+| of ISCALE, used in A9. Fp1 contains 10^^(abs(ISCALE)) using
+| the rounding mode as given in the following table (see
+| Coonen, p. 7.23 as ref.; however, the SCALE variable is
+| of opposite sign in bindec.sa from Coonen).
+|
+| Initial USE
+| FPCR[6:5] LAMBDA SIGN(X) FPCR[6:5]
+| ----------------------------------------------
+| RN 00 0 0 00/0 RN
+| RN 00 0 1 00/0 RN
+| RN 00 1 0 00/0 RN
+| RN 00 1 1 00/0 RN
+| RZ 01 0 0 11/3 RP
+| RZ 01 0 1 11/3 RP
+| RZ 01 1 0 10/2 RM
+| RZ 01 1 1 10/2 RM
+| RM 10 0 0 11/3 RP
+| RM 10 0 1 10/2 RM
+| RM 10 1 0 10/2 RM
+| RM 10 1 1 11/3 RP
+| RP 11 0 0 10/2 RM
+| RP 11 0 1 11/3 RP
+| RP 11 1 0 11/3 RP
+| RP 11 1 1 10/2 RM
+|
+| Register usage:
+| Input/Output
+| d0: exponent/scratch - final is 0
+| d2: x/0 or 24 for A9
+| d3: x/scratch - offset ptr into PTENRM array
+| d4: LEN/Unchanged
+| d5: 0/ICTR:LAMBDA
+| d6: ILOG/ILOG or k if ((k<=0)&(ILOG<k))
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/final result
+| a1: x/ptr to PTENRM array
+| a2: x/x
+| fp0: float(ILOG)/Unchanged
+| fp1: x/10^ISCALE
+| fp2: x/x
+| F_SCR1:x/x
+| F_SCR2:Abs(X) with $3fff exponent/Unchanged
+| L_SCR1:x/x
+| L_SCR2:first word of X packed/Unchanged
+
+A7_str:
+ tstl %d7 |test sign of k
+ bgts k_pos |if pos and > 0, skip this
+ cmpl %d6,%d7 |test k - ILOG
+ blts k_pos |if ILOG >= k, skip this
+ movel %d7,%d6 |if ((k<0) & (ILOG < k)) ILOG = k
+k_pos:
+ movel %d6,%d0 |calc ILOG + 1 - LEN in d0
+ addql #1,%d0 |add the 1
+ subl %d4,%d0 |sub off LEN
+ swap %d5 |use upper word of d5 for LAMBDA
+ clrw %d5 |set it zero initially
+ clrw %d2 |set up d2 for very small case
+ tstl %d0 |test sign of ISCALE
+ bges iscale |if pos, skip next inst
+ addqw #1,%d5 |if neg, set LAMBDA true
+ cmpl #0xffffecd4,%d0 |test iscale <= -4908
+ bgts no_inf |if false, skip rest
+ addil #24,%d0 |add in 24 to iscale
+ movel #24,%d2 |put 24 in d2 for A9
+no_inf:
+ negl %d0 |and take abs of ISCALE
+iscale:
+ fmoves FONE,%fp1 |init fp1 to 1
+ bfextu USER_FPCR(%a6){#26:#2},%d1 |get initial rmode bits
+ lslw #1,%d1 |put them in bits 2:1
+ addw %d5,%d1 |add in LAMBDA
+ lslw #1,%d1 |put them in bits 3:1
+ tstl L_SCR2(%a6) |test sign of original x
+ bges x_pos |if pos, don't set bit 0
+ addql #1,%d1 |if neg, set bit 0
+x_pos:
+ leal RBDTBL,%a2 |load rbdtbl base
+ moveb (%a2,%d1),%d3 |load d3 with new rmode
+ lsll #4,%d3 |put bits in proper position
+ fmovel %d3,%fpcr |load bits into fpu
+ lsrl #4,%d3 |put bits in proper position
+ tstb %d3 |decode new rmode for pten table
+ bnes not_rn |if zero, it is RN
+ leal PTENRN,%a1 |load a1 with RN table base
+ bras rmode |exit decode
+not_rn:
+ lsrb #1,%d3 |get lsb in carry
+ bccs not_rp |if carry clear, it is RM
+ leal PTENRP,%a1 |load a1 with RP table base
+ bras rmode |exit decode
+not_rp:
+ leal PTENRM,%a1 |load a1 with RM table base
+rmode:
+ clrl %d3 |clr table index
+e_loop:
+ lsrl #1,%d0 |shift next bit into carry
+ bccs e_next |if zero, skip the mul
+ fmulx (%a1,%d3),%fp1 |mul by 10**(d3_bit_no)
+e_next:
+ addl #12,%d3 |inc d3 to next pwrten table entry
+ tstl %d0 |test if ISCALE is zero
+ bnes e_loop |if not, loop
+
+
+| A8. Clr INEX; Force RZ.
+| The operation in A3 above may have set INEX2.
+| RZ mode is forced for the scaling operation to insure
+| only one rounding error. The grs bits are collected in
+| the INEX flag for use in A10.
+|
+| Register usage:
+| Input/Output
+
+ fmovel #0,%FPSR |clr INEX
+ fmovel #rz_mode,%FPCR |set RZ rounding mode
+
+
+| A9. Scale X -> Y.
+| The mantissa is scaled to the desired number of significant
+| digits. The excess digits are collected in INEX2. If mul,
+| Check d2 for excess 10 exponential value. If not zero,
+| the iscale value would have caused the pwrten calculation
+| to overflow. Only a negative iscale can cause this, so
+| multiply by 10^(d2), which is now only allowed to be 24,
+| with a multiply by 10^8 and 10^16, which is exact since
+| 10^24 is exact. If the input was denormalized, we must
+| create a busy stack frame with the mul command and the
+| two operands, and allow the fpu to complete the multiply.
+|
+| Register usage:
+| Input/Output
+| d0: FPCR with RZ mode/Unchanged
+| d2: 0 or 24/unchanged
+| d3: x/x
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA
+| d6: ILOG/Unchanged
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/final result
+| a1: ptr to PTENRM array/Unchanged
+| a2: x/x
+| fp0: float(ILOG)/X adjusted for SCALE (Y)
+| fp1: 10^ISCALE/Unchanged
+| fp2: x/x
+| F_SCR1:x/x
+| F_SCR2:Abs(X) with $3fff exponent/Unchanged
+| L_SCR1:x/x
+| L_SCR2:first word of X packed/Unchanged
+
+A9_str:
+ fmovex (%a0),%fp0 |load X from memory
+ fabsx %fp0 |use abs(X)
+ tstw %d5 |LAMBDA is in lower word of d5
+ bne sc_mul |if neg (LAMBDA = 1), scale by mul
+ fdivx %fp1,%fp0 |calculate X / SCALE -> Y to fp0
+ bras A10_st |branch to A10
+
+sc_mul:
+ tstb BINDEC_FLG(%a6) |check for denorm
+ beqs A9_norm |if norm, continue with mul
+ fmovemx %fp1-%fp1,-(%a7) |load ETEMP with 10^ISCALE
+ movel 8(%a0),-(%a7) |load FPTEMP with input arg
+ movel 4(%a0),-(%a7)
+ movel (%a0),-(%a7)
+ movel #18,%d3 |load count for busy stack
+A9_loop:
+ clrl -(%a7) |clear lword on stack
+ dbf %d3,A9_loop
+ moveb VER_TMP(%a6),(%a7) |write current version number
+ moveb #BUSY_SIZE-4,1(%a7) |write current busy size
+ moveb #0x10,0x44(%a7) |set fcefpte[15] bit
+ movew #0x0023,0x40(%a7) |load cmdreg1b with mul command
+ moveb #0xfe,0x8(%a7) |load all 1s to cu savepc
+ frestore (%a7)+ |restore frame to fpu for completion
+ fmulx 36(%a1),%fp0 |multiply fp0 by 10^8
+ fmulx 48(%a1),%fp0 |multiply fp0 by 10^16
+ bras A10_st
+A9_norm:
+ tstw %d2 |test for small exp case
+ beqs A9_con |if zero, continue as normal
+ fmulx 36(%a1),%fp0 |multiply fp0 by 10^8
+ fmulx 48(%a1),%fp0 |multiply fp0 by 10^16
+A9_con:
+ fmulx %fp1,%fp0 |calculate X * SCALE -> Y to fp0
+
+
+| A10. Or in INEX.
+| If INEX is set, round error occurred. This is compensated
+| for by 'or-ing' in the INEX2 flag to the lsb of Y.
+|
+| Register usage:
+| Input/Output
+| d0: FPCR with RZ mode/FPSR with INEX2 isolated
+| d2: x/x
+| d3: x/x
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA
+| d6: ILOG/Unchanged
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/final result
+| a1: ptr to PTENxx array/Unchanged
+| a2: x/ptr to FP_SCR2(a6)
+| fp0: Y/Y with lsb adjusted
+| fp1: 10^ISCALE/Unchanged
+| fp2: x/x
+
+A10_st:
+ fmovel %FPSR,%d0 |get FPSR
+ fmovex %fp0,FP_SCR2(%a6) |move Y to memory
+ leal FP_SCR2(%a6),%a2 |load a2 with ptr to FP_SCR2
+ btstl #9,%d0 |check if INEX2 set
+ beqs A11_st |if clear, skip rest
+ oril #1,8(%a2) |or in 1 to lsb of mantissa
+ fmovex FP_SCR2(%a6),%fp0 |write adjusted Y back to fpu
+
+
+| A11. Restore original FPCR; set size ext.
+| Perform FINT operation in the user's rounding mode. Keep
+| the size to extended. The sintdo entry point in the sint
+| routine expects the FPCR value to be in USER_FPCR for
+| mode and precision. The original FPCR is saved in L_SCR1.
+
+A11_st:
+ movel USER_FPCR(%a6),L_SCR1(%a6) |save it for later
+ andil #0x00000030,USER_FPCR(%a6) |set size to ext,
+| ;block exceptions
+
+
+| A12. Calculate YINT = FINT(Y) according to user's rounding mode.
+| The FPSP routine sintd0 is used. The output is in fp0.
+|
+| Register usage:
+| Input/Output
+| d0: FPSR with AINEX cleared/FPCR with size set to ext
+| d2: x/x/scratch
+| d3: x/x
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA/Unchanged
+| d6: ILOG/Unchanged
+| d7: k-factor/Unchanged
+| a0: ptr for original operand/src ptr for sintdo
+| a1: ptr to PTENxx array/Unchanged
+| a2: ptr to FP_SCR2(a6)/Unchanged
+| a6: temp pointer to FP_SCR2(a6) - orig value saved and restored
+| fp0: Y/YINT
+| fp1: 10^ISCALE/Unchanged
+| fp2: x/x
+| F_SCR1:x/x
+| F_SCR2:Y adjusted for inex/Y with original exponent
+| L_SCR1:x/original USER_FPCR
+| L_SCR2:first word of X packed/Unchanged
+
+A12_st:
+ moveml %d0-%d1/%a0-%a1,-(%a7) |save regs used by sintd0
+ movel L_SCR1(%a6),-(%a7)
+ movel L_SCR2(%a6),-(%a7)
+ leal FP_SCR2(%a6),%a0 |a0 is ptr to F_SCR2(a6)
+ fmovex %fp0,(%a0) |move Y to memory at FP_SCR2(a6)
+ tstl L_SCR2(%a6) |test sign of original operand
+ bges do_fint |if pos, use Y
+ orl #0x80000000,(%a0) |if neg, use -Y
+do_fint:
+ movel USER_FPSR(%a6),-(%a7)
+ bsr sintdo |sint routine returns int in fp0
+ moveb (%a7),USER_FPSR(%a6)
+ addl #4,%a7
+ movel (%a7)+,L_SCR2(%a6)
+ movel (%a7)+,L_SCR1(%a6)
+ moveml (%a7)+,%d0-%d1/%a0-%a1 |restore regs used by sint
+ movel L_SCR2(%a6),FP_SCR2(%a6) |restore original exponent
+ movel L_SCR1(%a6),USER_FPCR(%a6) |restore user's FPCR
+
+
+| A13. Check for LEN digits.
+| If the int operation results in more than LEN digits,
+| or less than LEN -1 digits, adjust ILOG and repeat from
+| A6. This test occurs only on the first pass. If the
+| result is exactly 10^LEN, decrement ILOG and divide
+| the mantissa by 10. The calculation of 10^LEN cannot
+| be inexact, since all powers of ten up to 10^27 are exact
+| in extended precision, so the use of a previous power-of-ten
+| table will introduce no error.
+|
+|
+| Register usage:
+| Input/Output
+| d0: FPCR with size set to ext/scratch final = 0
+| d2: x/x
+| d3: x/scratch final = x
+| d4: LEN/LEN adjusted
+| d5: ICTR:LAMBDA/LAMBDA:ICTR
+| d6: ILOG/ILOG adjusted
+| d7: k-factor/Unchanged
+| a0: pointer into memory for packed bcd string formation
+| a1: ptr to PTENxx array/Unchanged
+| a2: ptr to FP_SCR2(a6)/Unchanged
+| fp0: int portion of Y/abs(YINT) adjusted
+| fp1: 10^ISCALE/Unchanged
+| fp2: x/10^LEN
+| F_SCR1:x/x
+| F_SCR2:Y with original exponent/Unchanged
+| L_SCR1:original USER_FPCR/Unchanged
+| L_SCR2:first word of X packed/Unchanged
+
+A13_st:
+ swap %d5 |put ICTR in lower word of d5
+ tstw %d5 |check if ICTR = 0
+ bne not_zr |if non-zero, go to second test
+|
+| Compute 10^(LEN-1)
+|
+ fmoves FONE,%fp2 |init fp2 to 1.0
+ movel %d4,%d0 |put LEN in d0
+ subql #1,%d0 |d0 = LEN -1
+ clrl %d3 |clr table index
+l_loop:
+ lsrl #1,%d0 |shift next bit into carry
+ bccs l_next |if zero, skip the mul
+ fmulx (%a1,%d3),%fp2 |mul by 10**(d3_bit_no)
+l_next:
+ addl #12,%d3 |inc d3 to next pwrten table entry
+ tstl %d0 |test if LEN is zero
+ bnes l_loop |if not, loop
+|
+| 10^LEN-1 is computed for this test and A14. If the input was
+| denormalized, check only the case in which YINT > 10^LEN.
+|
+ tstb BINDEC_FLG(%a6) |check if input was norm
+ beqs A13_con |if norm, continue with checking
+ fabsx %fp0 |take abs of YINT
+ bra test_2
+|
+| Compare abs(YINT) to 10^(LEN-1) and 10^LEN
+|
+A13_con:
+ fabsx %fp0 |take abs of YINT
+ fcmpx %fp2,%fp0 |compare abs(YINT) with 10^(LEN-1)
+ fbge test_2 |if greater, do next test
+ subql #1,%d6 |subtract 1 from ILOG
+ movew #1,%d5 |set ICTR
+ fmovel #rm_mode,%FPCR |set rmode to RM
+ fmuls FTEN,%fp2 |compute 10^LEN
+ bra A6_str |return to A6 and recompute YINT
+test_2:
+ fmuls FTEN,%fp2 |compute 10^LEN
+ fcmpx %fp2,%fp0 |compare abs(YINT) with 10^LEN
+ fblt A14_st |if less, all is ok, go to A14
+ fbgt fix_ex |if greater, fix and redo
+ fdivs FTEN,%fp0 |if equal, divide by 10
+ addql #1,%d6 | and inc ILOG
+ bras A14_st | and continue elsewhere
+fix_ex:
+ addql #1,%d6 |increment ILOG by 1
+ movew #1,%d5 |set ICTR
+ fmovel #rm_mode,%FPCR |set rmode to RM
+ bra A6_str |return to A6 and recompute YINT
+|
+| Since ICTR <> 0, we have already been through one adjustment,
+| and shouldn't have another; this is to check if abs(YINT) = 10^LEN
+| 10^LEN is again computed using whatever table is in a1 since the
+| value calculated cannot be inexact.
+|
+not_zr:
+ fmoves FONE,%fp2 |init fp2 to 1.0
+ movel %d4,%d0 |put LEN in d0
+ clrl %d3 |clr table index
+z_loop:
+ lsrl #1,%d0 |shift next bit into carry
+ bccs z_next |if zero, skip the mul
+ fmulx (%a1,%d3),%fp2 |mul by 10**(d3_bit_no)
+z_next:
+ addl #12,%d3 |inc d3 to next pwrten table entry
+ tstl %d0 |test if LEN is zero
+ bnes z_loop |if not, loop
+ fabsx %fp0 |get abs(YINT)
+ fcmpx %fp2,%fp0 |check if abs(YINT) = 10^LEN
+ fbne A14_st |if not, skip this
+ fdivs FTEN,%fp0 |divide abs(YINT) by 10
+ addql #1,%d6 |and inc ILOG by 1
+ addql #1,%d4 | and inc LEN
+ fmuls FTEN,%fp2 | if LEN++, the get 10^^LEN
+
+
+| A14. Convert the mantissa to bcd.
+| The binstr routine is used to convert the LEN digit
+| mantissa to bcd in memory. The input to binstr is
+| to be a fraction; i.e. (mantissa)/10^LEN and adjusted
+| such that the decimal point is to the left of bit 63.
+| The bcd digits are stored in the correct position in
+| the final string area in memory.
+|
+|
+| Register usage:
+| Input/Output
+| d0: x/LEN call to binstr - final is 0
+| d1: x/0
+| d2: x/ms 32-bits of mant of abs(YINT)
+| d3: x/ls 32-bits of mant of abs(YINT)
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA/LAMBDA:ICTR
+| d6: ILOG
+| d7: k-factor/Unchanged
+| a0: pointer into memory for packed bcd string formation
+| /ptr to first mantissa byte in result string
+| a1: ptr to PTENxx array/Unchanged
+| a2: ptr to FP_SCR2(a6)/Unchanged
+| fp0: int portion of Y/abs(YINT) adjusted
+| fp1: 10^ISCALE/Unchanged
+| fp2: 10^LEN/Unchanged
+| F_SCR1:x/Work area for final result
+| F_SCR2:Y with original exponent/Unchanged
+| L_SCR1:original USER_FPCR/Unchanged
+| L_SCR2:first word of X packed/Unchanged
+
+A14_st:
+ fmovel #rz_mode,%FPCR |force rz for conversion
+ fdivx %fp2,%fp0 |divide abs(YINT) by 10^LEN
+ leal FP_SCR1(%a6),%a0
+ fmovex %fp0,(%a0) |move abs(YINT)/10^LEN to memory
+ movel 4(%a0),%d2 |move 2nd word of FP_RES to d2
+ movel 8(%a0),%d3 |move 3rd word of FP_RES to d3
+ clrl 4(%a0) |zero word 2 of FP_RES
+ clrl 8(%a0) |zero word 3 of FP_RES
+ movel (%a0),%d0 |move exponent to d0
+ swap %d0 |put exponent in lower word
+ beqs no_sft |if zero, don't shift
+ subil #0x3ffd,%d0 |sub bias less 2 to make fract
+ tstl %d0 |check if > 1
+ bgts no_sft |if so, don't shift
+ negl %d0 |make exp positive
+m_loop:
+ lsrl #1,%d2 |shift d2:d3 right, add 0s
+ roxrl #1,%d3 |the number of places
+ dbf %d0,m_loop |given in d0
+no_sft:
+ tstl %d2 |check for mantissa of zero
+ bnes no_zr |if not, go on
+ tstl %d3 |continue zero check
+ beqs zer_m |if zero, go directly to binstr
+no_zr:
+ clrl %d1 |put zero in d1 for addx
+ addil #0x00000080,%d3 |inc at bit 7
+ addxl %d1,%d2 |continue inc
+ andil #0xffffff80,%d3 |strip off lsb not used by 882
+zer_m:
+ movel %d4,%d0 |put LEN in d0 for binstr call
+ addql #3,%a0 |a0 points to M16 byte in result
+ bsr binstr |call binstr to convert mant
+
+
+| A15. Convert the exponent to bcd.
+| As in A14 above, the exp is converted to bcd and the
+| digits are stored in the final string.
+|
+| Digits are stored in L_SCR1(a6) on return from BINDEC as:
+|
+| 32 16 15 0
+| -----------------------------------------
+| | 0 | e3 | e2 | e1 | e4 | X | X | X |
+| -----------------------------------------
+|
+| And are moved into their proper places in FP_SCR1. If digit e4
+| is non-zero, OPERR is signaled. In all cases, all 4 digits are
+| written as specified in the 881/882 manual for packed decimal.
+|
+| Register usage:
+| Input/Output
+| d0: x/LEN call to binstr - final is 0
+| d1: x/scratch (0);shift count for final exponent packing
+| d2: x/ms 32-bits of exp fraction/scratch
+| d3: x/ls 32-bits of exp fraction
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA/LAMBDA:ICTR
+| d6: ILOG
+| d7: k-factor/Unchanged
+| a0: ptr to result string/ptr to L_SCR1(a6)
+| a1: ptr to PTENxx array/Unchanged
+| a2: ptr to FP_SCR2(a6)/Unchanged
+| fp0: abs(YINT) adjusted/float(ILOG)
+| fp1: 10^ISCALE/Unchanged
+| fp2: 10^LEN/Unchanged
+| F_SCR1:Work area for final result/BCD result
+| F_SCR2:Y with original exponent/ILOG/10^4
+| L_SCR1:original USER_FPCR/Exponent digits on return from binstr
+| L_SCR2:first word of X packed/Unchanged
+
+A15_st:
+ tstb BINDEC_FLG(%a6) |check for denorm
+ beqs not_denorm
+ ftstx %fp0 |test for zero
+ fbeq den_zero |if zero, use k-factor or 4933
+ fmovel %d6,%fp0 |float ILOG
+ fabsx %fp0 |get abs of ILOG
+ bras convrt
+den_zero:
+ tstl %d7 |check sign of the k-factor
+ blts use_ilog |if negative, use ILOG
+ fmoves F4933,%fp0 |force exponent to 4933
+ bras convrt |do it
+use_ilog:
+ fmovel %d6,%fp0 |float ILOG
+ fabsx %fp0 |get abs of ILOG
+ bras convrt
+not_denorm:
+ ftstx %fp0 |test for zero
+ fbne not_zero |if zero, force exponent
+ fmoves FONE,%fp0 |force exponent to 1
+ bras convrt |do it
+not_zero:
+ fmovel %d6,%fp0 |float ILOG
+ fabsx %fp0 |get abs of ILOG
+convrt:
+ fdivx 24(%a1),%fp0 |compute ILOG/10^4
+ fmovex %fp0,FP_SCR2(%a6) |store fp0 in memory
+ movel 4(%a2),%d2 |move word 2 to d2
+ movel 8(%a2),%d3 |move word 3 to d3
+ movew (%a2),%d0 |move exp to d0
+ beqs x_loop_fin |if zero, skip the shift
+ subiw #0x3ffd,%d0 |subtract off bias
+ negw %d0 |make exp positive
+x_loop:
+ lsrl #1,%d2 |shift d2:d3 right
+ roxrl #1,%d3 |the number of places
+ dbf %d0,x_loop |given in d0
+x_loop_fin:
+ clrl %d1 |put zero in d1 for addx
+ addil #0x00000080,%d3 |inc at bit 6
+ addxl %d1,%d2 |continue inc
+ andil #0xffffff80,%d3 |strip off lsb not used by 882
+ movel #4,%d0 |put 4 in d0 for binstr call
+ leal L_SCR1(%a6),%a0 |a0 is ptr to L_SCR1 for exp digits
+ bsr binstr |call binstr to convert exp
+ movel L_SCR1(%a6),%d0 |load L_SCR1 lword to d0
+ movel #12,%d1 |use d1 for shift count
+ lsrl %d1,%d0 |shift d0 right by 12
+ bfins %d0,FP_SCR1(%a6){#4:#12} |put e3:e2:e1 in FP_SCR1
+ lsrl %d1,%d0 |shift d0 right by 12
+ bfins %d0,FP_SCR1(%a6){#16:#4} |put e4 in FP_SCR1
+ tstb %d0 |check if e4 is zero
+ beqs A16_st |if zero, skip rest
+ orl #opaop_mask,USER_FPSR(%a6) |set OPERR & AIOP in USER_FPSR
+
+
+| A16. Write sign bits to final string.
+| Sigma is bit 31 of initial value; RHO is bit 31 of d6 (ILOG).
+|
+| Register usage:
+| Input/Output
+| d0: x/scratch - final is x
+| d2: x/x
+| d3: x/x
+| d4: LEN/Unchanged
+| d5: ICTR:LAMBDA/LAMBDA:ICTR
+| d6: ILOG/ILOG adjusted
+| d7: k-factor/Unchanged
+| a0: ptr to L_SCR1(a6)/Unchanged
+| a1: ptr to PTENxx array/Unchanged
+| a2: ptr to FP_SCR2(a6)/Unchanged
+| fp0: float(ILOG)/Unchanged
+| fp1: 10^ISCALE/Unchanged
+| fp2: 10^LEN/Unchanged
+| F_SCR1:BCD result with correct signs
+| F_SCR2:ILOG/10^4
+| L_SCR1:Exponent digits on return from binstr
+| L_SCR2:first word of X packed/Unchanged
+
+A16_st:
+ clrl %d0 |clr d0 for collection of signs
+ andib #0x0f,FP_SCR1(%a6) |clear first nibble of FP_SCR1
+ tstl L_SCR2(%a6) |check sign of original mantissa
+ bges mant_p |if pos, don't set SM
+ moveql #2,%d0 |move 2 in to d0 for SM
+mant_p:
+ tstl %d6 |check sign of ILOG
+ bges wr_sgn |if pos, don't set SE
+ addql #1,%d0 |set bit 0 in d0 for SE
+wr_sgn:
+ bfins %d0,FP_SCR1(%a6){#0:#2} |insert SM and SE into FP_SCR1
+
+| Clean up and restore all registers used.
+
+ fmovel #0,%FPSR |clear possible inex2/ainex bits
+ fmovemx (%a7)+,%fp0-%fp2
+ moveml (%a7)+,%d2-%d7/%a2
+ rts
+
+ |end
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