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1|
2| binstr.sa 3.3 12/19/90
3|
4|
5| Description: Converts a 64-bit binary integer to bcd.
6|
7| Input: 64-bit binary integer in d2:d3, desired length (LEN) in
8| d0, and a pointer to start in memory for bcd characters
9| in d0. (This pointer must point to byte 4 of the first
10| lword of the packed decimal memory string.)
11|
12| Output: LEN bcd digits representing the 64-bit integer.
13|
14| Algorithm:
15| The 64-bit binary is assumed to have a decimal point before
16| bit 63. The fraction is multiplied by 10 using a mul by 2
17| shift and a mul by 8 shift. The bits shifted out of the
18| msb form a decimal digit. This process is iterated until
19| LEN digits are formed.
20|
21| A1. Init d7 to 1. D7 is the byte digit counter, and if 1, the
22| digit formed will be assumed the least significant. This is
23| to force the first byte formed to have a 0 in the upper 4 bits.
24|
25| A2. Beginning of the loop:
26| Copy the fraction in d2:d3 to d4:d5.
27|
28| A3. Multiply the fraction in d2:d3 by 8 using bit-field
29| extracts and shifts. The three msbs from d2 will go into
30| d1.
31|
32| A4. Multiply the fraction in d4:d5 by 2 using shifts. The msb
33| will be collected by the carry.
34|
35| A5. Add using the carry the 64-bit quantities in d2:d3 and d4:d5
36| into d2:d3. D1 will contain the bcd digit formed.
37|
38| A6. Test d7. If zero, the digit formed is the ms digit. If non-
39| zero, it is the ls digit. Put the digit in its place in the
40| upper word of d0. If it is the ls digit, write the word
41| from d0 to memory.
42|
43| A7. Decrement d6 (LEN counter) and repeat the loop until zero.
44|
45| Implementation Notes:
46|
47| The registers are used as follows:
48|
49| d0: LEN counter
50| d1: temp used to form the digit
51| d2: upper 32-bits of fraction for mul by 8
52| d3: lower 32-bits of fraction for mul by 8
53| d4: upper 32-bits of fraction for mul by 2
54| d5: lower 32-bits of fraction for mul by 2
55| d6: temp for bit-field extracts
56| d7: byte digit formation word;digit count {0,1}
57| a0: pointer into memory for packed bcd string formation
58|
59
60| Copyright (C) Motorola, Inc. 1990
61| All Rights Reserved
62|
63| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
64| The copyright notice above does not evidence any
65| actual or intended publication of such source code.
66
67|BINSTR idnt 2,1 | Motorola 040 Floating Point Software Package
68
69 |section 8
70
71#include "fpsp.h"
72
73 .global binstr
74binstr:
75 moveml %d0-%d7,-(%a7)
76|
77| A1: Init d7
78|
79 moveql #1,%d7 |init d7 for second digit
80 subql #1,%d0 |for dbf d0 would have LEN+1 passes
81|
82| A2. Copy d2:d3 to d4:d5. Start loop.
83|
84loop:
85 movel %d2,%d4 |copy the fraction before muls
86 movel %d3,%d5 |to d4:d5
87|
88| A3. Multiply d2:d3 by 8; extract msbs into d1.
89|
90 bfextu %d2{#0:#3},%d1 |copy 3 msbs of d2 into d1
91 asll #3,%d2 |shift d2 left by 3 places
92 bfextu %d3{#0:#3},%d6 |copy 3 msbs of d3 into d6
93 asll #3,%d3 |shift d3 left by 3 places
94 orl %d6,%d2 |or in msbs from d3 into d2
95|
96| A4. Multiply d4:d5 by 2; add carry out to d1.
97|
98 asll #1,%d5 |mul d5 by 2
99 roxll #1,%d4 |mul d4 by 2
100 swap %d6 |put 0 in d6 lower word
101 addxw %d6,%d1 |add in extend from mul by 2
102|
103| A5. Add mul by 8 to mul by 2. D1 contains the digit formed.
104|
105 addl %d5,%d3 |add lower 32 bits
106 nop |ERRATA ; FIX #13 (Rev. 1.2 6/6/90)
107 addxl %d4,%d2 |add with extend upper 32 bits
108 nop |ERRATA ; FIX #13 (Rev. 1.2 6/6/90)
109 addxw %d6,%d1 |add in extend from add to d1
110 swap %d6 |with d6 = 0; put 0 in upper word
111|
112| A6. Test d7 and branch.
113|
114 tstw %d7 |if zero, store digit & to loop
115 beqs first_d |if non-zero, form byte & write
116sec_d:
117 swap %d7 |bring first digit to word d7b
118 aslw #4,%d7 |first digit in upper 4 bits d7b
119 addw %d1,%d7 |add in ls digit to d7b
120 moveb %d7,(%a0)+ |store d7b byte in memory
121 swap %d7 |put LEN counter in word d7a
122 clrw %d7 |set d7a to signal no digits done
123 dbf %d0,loop |do loop some more!
124 bras end_bstr |finished, so exit
125first_d:
126 swap %d7 |put digit word in d7b
127 movew %d1,%d7 |put new digit in d7b
128 swap %d7 |put LEN counter in word d7a
129 addqw #1,%d7 |set d7a to signal first digit done
130 dbf %d0,loop |do loop some more!
131 swap %d7 |put last digit in string
132 lslw #4,%d7 |move it to upper 4 bits
133 moveb %d7,(%a0)+ |store it in memory string
134|
135| Clean up and return with result in fp0.
136|
137end_bstr:
138 moveml (%a7)+,%d0-%d7
139 rts
140 |end