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| For details on the license for this file, please see the
64| file, README, in this same directory.
65
66|BINSTR idnt 2,1 | Motorola 040 Floating Point Software Package
67
68 |section 8
69
70#include "fpsp.h"
71
72 .global binstr
73binstr:
74 moveml %d0-%d7,-(%a7)
75|
76| A1: Init d7
77|
78 moveql
79 subql
80|
81| A2. Copy d2:d3 to d4:d5. Start loop.
82|
83loop:
84 movel %d2,%d4 |copy the fraction before muls
85 movel %d3,%d5 |to d4:d5
86|
87| A3. Multiply d2:d3 by 8; extract msbs into d1.
88|
89 bfextu %d2{
90 asll
91 bfextu %d3{
92 asll
93 orl %d6,%d2 |or in msbs from d3 into d2
94|
95| A4. Multiply d4:d5 by 2; add carry out to d1.
96|
97 asll
98 roxll
99 swap %d6 |put 0 in d6 lower word
100 addxw %d6,%d1 |add in extend from mul by 2
101|
102| A5. Add mul by 8 to mul by 2. D1 contains the digit formed.
103|
104 addl %d5,%d3 |add lower 32 bits
105 nop |ERRATA ; FIX
106 addxl %d4,%d2 |add with extend upper 32 bits
107 nop |ERRATA ; FIX
108 addxw %d6,%d1 |add in extend from add to d1
109 swap %d6 |with d6 = 0; put 0 in upper word
110|
111| A6. Test d7 and branch.
112|
113 tstw %d7 |if zero, store digit & to loop
114 beqs first_d |if non-zero, form byte & write
115sec_d:
116 swap %d7 |bring first digit to word d7b
117 aslw
118 addw %d1,%d7 |add in ls digit to d7b
119 moveb %d7,(%a0)+ |store d7b byte in memory
120 swap %d7 |put LEN counter in word d7a
121 clrw %d7 |set d7a to signal no digits done
122 dbf %d0,loop |do loop some more!
123 bras end_bstr |finished, so exit
124first_d:
125 swap %d7 |put digit word in d7b
126 movew %d1,%d7 |put new digit in d7b
127 swap %d7 |put LEN counter in word d7a
128 addqw
129 dbf %d0,loop |do loop some more!
130 swap %d7 |put last digit in string
131 lslw
132 moveb %d7,(%a0)+ |store it in memory string
133|
134| Clean up and return with result in fp0.
135|
136end_bstr:
137 moveml (%a7)+,%d0-%d7
138 rts
139 |end
140
