Commit | Line | Data |
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1da177e4 LT |
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 | | | |
e00d82d0 MW |
63 | | For details on the license for this file, please see the |
64 | | file, README, in this same directory. | |
1da177e4 LT |
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 | |
73 | binstr: | |
74 | moveml %d0-%d7,-(%a7) | |
75 | | | |
76 | | A1: Init d7 | |
77 | | | |
78 | moveql #1,%d7 |init d7 for second digit | |
79 | subql #1,%d0 |for dbf d0 would have LEN+1 passes | |
80 | | | |
81 | | A2. Copy d2:d3 to d4:d5. Start loop. | |
82 | | | |
83 | loop: | |
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{#0:#3},%d1 |copy 3 msbs of d2 into d1 | |
90 | asll #3,%d2 |shift d2 left by 3 places | |
91 | bfextu %d3{#0:#3},%d6 |copy 3 msbs of d3 into d6 | |
92 | asll #3,%d3 |shift d3 left by 3 places | |
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 #1,%d5 |mul d5 by 2 | |
98 | roxll #1,%d4 |mul d4 by 2 | |
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 #13 (Rev. 1.2 6/6/90) | |
106 | addxl %d4,%d2 |add with extend upper 32 bits | |
107 | nop |ERRATA ; FIX #13 (Rev. 1.2 6/6/90) | |
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 | |
115 | sec_d: | |
116 | swap %d7 |bring first digit to word d7b | |
117 | aslw #4,%d7 |first digit in upper 4 bits d7b | |
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 | |
124 | first_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 #1,%d7 |set d7a to signal first digit done | |
129 | dbf %d0,loop |do loop some more! | |
130 | swap %d7 |put last digit in string | |
131 | lslw #4,%d7 |move it to upper 4 bits | |
132 | moveb %d7,(%a0)+ |store it in memory string | |
133 | | | |
134 | | Clean up and return with result in fp0. | |
135 | | | |
136 | end_bstr: | |
137 | moveml (%a7)+,%d0-%d7 | |
138 | rts | |
139 | |end |