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 | | 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