diff options
Diffstat (limited to 'arch/m68k/fpsp040/binstr.S')
| -rw-r--r-- | arch/m68k/fpsp040/binstr.S | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/arch/m68k/fpsp040/binstr.S b/arch/m68k/fpsp040/binstr.S new file mode 100644 index 000000000..8a05ba92a --- /dev/null +++ b/arch/m68k/fpsp040/binstr.S @@ -0,0 +1,139 @@ +| +| 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 |