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 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 140