Binary-Coded Decimal Instructions - Motorola MC68030 User Manual

Instruction Set Summary
3.2.7 Binary–coded Decimal Instructions
Five instructions support operations on binary-coded decimal (BCD) numbers. The
arithmetic operations on packed BCD numbers are add decimal with extend (ABCD),
subtract decimal with extend (SBCD), and negate decimal with extend (NBCD). PACK and
UNPACK instructions aid in the conversion of byte encoded numeric data, such as ASCII or
EBCDIC strings, to BCD data and vice versa. Table 3–7 is a summary of the BCD
operations.
Instruction Operand Syntax
ABCD Dn,Dn
–(An)
〈ea〉
NBCD
PACK –(An),–(An)
#〈data〉
Dn,Dn,# 〈data〉
SBCD Dn,Dn
–(An),–(An)
UNPK –(An)
#〈data〉
Dn,Dn,#〈data〉
3-10
Table 3-7. BCD Operations
Operand Size
8 source + destination
10
8
8 0 - destination
unpackaged source + immediate data → packed
16→8
destination
16→8
8 destination
8
packed source → unpacked source
8→16
unpacked source + immediate data →
8→16
unpacked destination
MC68030 USER'S MANUAL
Operation
+ X → destination
10
–X → destination
10
– X → destination
- source
10 10
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