Joel,
You must have missed my solution from a couple of days ago. It uses six (6)
instructions with minimal table space.
Here it is again.
MVC OBUFF,IBYTE Copy the byte to be converted @xxnnnnn
MVC OBUFF+1(7),OBUFF @xxnnnnn
* Propagate the byte to all eight @xxnnnnn
* (8) positions @xxnnnnn
NC OBUFF,=X'8040201008040201' @xxnnnnn
* Mask the appropriate bit in @xxnnnnn
* each byte @xxnnnnn
MVO WORK5,OBUFF(4) Shift the high-order nibbles @xxnnnnn
* associated with the high-order @xxnnnnn
* bits to the corresponding @xxnnnnn
* low-order-nibbles in the work @xxnnnnn
* buffer @xxnnnnn
MVC OBUFF(4),WORK5 Return the low-order nibbles to @xxnnnnn
* the output buffer @xxnnnnn
TR OBUFF,=C'011-1---1' @xxnnnnn
* Convert the bits masks contained @xxnnnnn
* in the output buffer to EBCDIC @xxnnnnn
* binary digits (0,1) @xxnnnnn
IBYTE DC B'01110101' Sample Input Value @xxnnnnn
WORK5 DC X'0000000000' Work Area @xxnnnnn
OBUFF DS CL8 Output Value @xxnnnnn
LTORG , Literal Pool @xxnnnnn
Summary of storage requirements:
36 Bytes - Instructions
17 Bytes - Literals
1 Byte - Input Buffer
5 Bytes - Work Area
8 Bytes - Output Area
67 Bytes - Total
6 Instructions - Total
The use of the MVO/MVC sequence eliminates the need for a large translation
table. Just 9 bytes are required.
John P Baker
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf
Of Joel C. Ewing
Sent: Friday, December 14, 2007 10:48 PM
To: [email protected]
Subject: Re: Mainframe Assembler Coding Contest
Did the original problem statement require this be done with a loop? If
not, why not use straight line code with only 4 executed instructions
instead of the 28 or 29 with the loops as above? For Example:
MVC OUTCHAR(1),INBYTE
MVC OUTCHAR+1(7),OUTCHAR 8 COPIES OF ORIGINAL BYTE
NC OUTCHAR,=XL8'8040201008040201'
TR OUTCHAR,BIT2CHR
...
OUTCHAR DS CL8
INBYTE DC B'10101011'
* THE ONLY USED BYTES BELOW ARE
* AT BIT2CHR +0,+1,+2,+4,+8,+16,+32,+64, AND +128
BIT2CHR DC C'0',128C'1'
This requires more storage because of the table, but that would even out
if multiple conversions were needed within the same program - or if you
got sufficiently clever (and obscure) to use the 120 unused bytes in the
129 byte table for other purposes.
--
Joel C. Ewing, Fort Smith, AR [EMAIL PROTECTED]
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