cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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binstr.S (4302B)


      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
     73binstr:
     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|
     83loop:
     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
    115sec_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
    124first_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|
    136end_bstr:
    137	moveml	(%a7)+,%d0-%d7
    138	rts
    139	|end