| | |
| | 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 |
| | |
| | For details on the license for this file, please see the |
| | file, README, in this same directory. |
| |
| |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 |