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+|
+| binstr.sa 3.3 12/19/90
+|
+|
+| Description: Converts a 64-bit binary integer to bcd.
+|
+| Input: 64-bit binary integer in d2:d3, desired length (LEN) in
+| d0, and a pointer to start in memory for bcd characters
+| in d0. (This pointer must point to byte 4 of the first
+| lword of the packed decimal memory string.)
+|
+| Output: LEN bcd digits representing the 64-bit integer.
+|
+| Algorithm:
+| The 64-bit binary is assumed to have a decimal point before
+| bit 63. The fraction is multiplied by 10 using a mul by 2
+| shift and a mul by 8 shift. The bits shifted out of the
+| msb form a decimal digit. This process is iterated until
+| LEN digits are formed.
+|
+| A1. Init d7 to 1. D7 is the byte digit counter, and if 1, the
+| digit formed will be assumed the least significant. This is
+| to force the first byte formed to have a 0 in the upper 4 bits.
+|
+| A2. Beginning of the loop:
+| Copy the fraction in d2:d3 to d4:d5.
+|
+| A3. Multiply the fraction in d2:d3 by 8 using bit-field
+| extracts and shifts. The three msbs from d2 will go into
+| d1.
+|
+| A4. Multiply the fraction in d4:d5 by 2 using shifts. The msb
+| will be collected by the carry.
+|
+| A5. Add using the carry the 64-bit quantities in d2:d3 and d4:d5
+| into d2:d3. D1 will contain the bcd digit formed.
+|
+| A6. Test d7. If zero, the digit formed is the ms digit. If non-
+| zero, it is the ls digit. Put the digit in its place in the
+| upper word of d0. If it is the ls digit, write the word
+| from d0 to memory.
+|
+| A7. Decrement d6 (LEN counter) and repeat the loop until zero.
+|
+| Implementation Notes:
+|
+| The registers are used as follows:
+|
+| d0: LEN counter
+| d1: temp used to form the digit
+| d2: upper 32-bits of fraction for mul by 8
+| d3: lower 32-bits of fraction for mul by 8
+| d4: upper 32-bits of fraction for mul by 2
+| d5: lower 32-bits of fraction for mul by 2
+| d6: temp for bit-field extracts
+| d7: byte digit formation word;digit count {0,1}
+| a0: pointer into memory for packed bcd string formation
+|
+
+| Copyright (C) Motorola, Inc. 1990
+| All Rights Reserved
+|
+| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
+| The copyright notice above does not evidence any
+| actual or intended publication of such source code.
+
+|BINSTR idnt 2,1 | Motorola 040 Floating Point Software Package
+
+ |section 8
+
+#include "fpsp.h"
+
+ .global binstr
+binstr:
+ moveml %d0-%d7,-(%a7)
+|
+| A1: Init d7
+|
+ moveql #1,%d7 |init d7 for second digit
+ subql #1,%d0 |for dbf d0 would have LEN+1 passes
+|
+| A2. Copy d2:d3 to d4:d5. Start loop.
+|
+loop:
+ movel %d2,%d4 |copy the fraction before muls
+ movel %d3,%d5 |to d4:d5
+|
+| A3. Multiply d2:d3 by 8; extract msbs into d1.
+|
+ bfextu %d2{#0:#3},%d1 |copy 3 msbs of d2 into d1
+ asll #3,%d2 |shift d2 left by 3 places
+ bfextu %d3{#0:#3},%d6 |copy 3 msbs of d3 into d6
+ asll #3,%d3 |shift d3 left by 3 places
+ orl %d6,%d2 |or in msbs from d3 into d2
+|
+| A4. Multiply d4:d5 by 2; add carry out to d1.
+|
+ asll #1,%d5 |mul d5 by 2
+ roxll #1,%d4 |mul d4 by 2
+ swap %d6 |put 0 in d6 lower word
+ addxw %d6,%d1 |add in extend from mul by 2
+|
+| A5. Add mul by 8 to mul by 2. D1 contains the digit formed.
+|
+ addl %d5,%d3 |add lower 32 bits
+ nop |ERRATA ; FIX #13 (Rev. 1.2 6/6/90)
+ addxl %d4,%d2 |add with extend upper 32 bits
+ nop |ERRATA ; FIX #13 (Rev. 1.2 6/6/90)
+ addxw %d6,%d1 |add in extend from add to d1
+ swap %d6 |with d6 = 0; put 0 in upper word
+|
+| A6. Test d7 and branch.
+|
+ tstw %d7 |if zero, store digit & to loop
+ beqs first_d |if non-zero, form byte & write
+sec_d:
+ swap %d7 |bring first digit to word d7b
+ aslw #4,%d7 |first digit in upper 4 bits d7b
+ addw %d1,%d7 |add in ls digit to d7b
+ moveb %d7,(%a0)+ |store d7b byte in memory
+ swap %d7 |put LEN counter in word d7a
+ clrw %d7 |set d7a to signal no digits done
+ dbf %d0,loop |do loop some more!
+ bras end_bstr |finished, so exit
+first_d:
+ swap %d7 |put digit word in d7b
+ movew %d1,%d7 |put new digit in d7b
+ swap %d7 |put LEN counter in word d7a
+ addqw #1,%d7 |set d7a to signal first digit done
+ dbf %d0,loop |do loop some more!
+ swap %d7 |put last digit in string
+ lslw #4,%d7 |move it to upper 4 bits
+ moveb %d7,(%a0)+ |store it in memory string
+|
+| Clean up and return with result in fp0.
+|
+end_bstr:
+ moveml (%a7)+,%d0-%d7
+ rts
+ |end