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Diffstat (limited to 'c/src/lib/libcpu/m68k/m68040/fpsp/binstr.S')
| -rw-r--r-- | c/src/lib/libcpu/m68k/m68040/fpsp/binstr.S | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/m68k/m68040/fpsp/binstr.S b/c/src/lib/libcpu/m68k/m68040/fpsp/binstr.S new file mode 100644 index 0000000000..96f2592995 --- /dev/null +++ b/c/src/lib/libcpu/m68k/m68040/fpsp/binstr.S @@ -0,0 +1,141 @@ +// +// $Id$ +// +// 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 +// +// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA +// The copyright notice above does not evidence any +// actual or intended publication of such source code. + +//BINSTR idnt 2,1 | Motorola 040 Floating Point Software Package + + |section 8 + +#include "fpsp.defs" + + .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 |