HLASM - CLCL = Compare Logical Characters Long
The opcode of the CLCL instruction is X'0F'.
- Compare nonnumeric data fields longer than 256 bytes.
- Compare nonnumeric data fields of unequal lengths.
- Even-odd register pair containing first comparand address and length:
- First comparand address in the even register.
- First comparand field length in the low-order 24 bits of the
32-bit odd register.
- Even-odd register pair containing second comparand address, length and
- Second comparand address in the even register.
- Second comparand field length in the low-order 24 bits of the
odd 32-bit register.
- Pad value in the high-order 8 bits of the odd 32-bit register.
- The processor compares the data from both fields. If their lengths are
unequal, the shorter field is treated as if it were extended with as many
padding characters as needed to make it as long as the other field.
- The processor sets the condition code as follows:
- 0 = Operands are equal.
- 1 = First operand is higher than the second.
- 2 = First operand is lower than the second.
- 3 = Not used.
- If both lengths are 0, then the fields are considered equal.
- CLC compares fields up to 256 bytes (inclusive)
- CLCLE compares fields longer than 16M bytes.
- The CLCL instruction was not in the original instruction set,
but has been around for a very long time.
- The PSW's Amode setting determines how many bits are used for both
comparand field addresses.
- CLCL is an interruptible instruction. That is, its execution can be
interrupted and later resumed by the operating system. To the programmer
this is a transparent process, but in dumps intermediate results may show
up. This happens because the processor will adjust the contents of the four
registers according to the progress made.
- After CLCL completes the contents of the four input registers are
YREGS * Define register names
L R0,TABLE * Point to field
L R1,TABLE_END * Point end of field
SR R1,R0 * Obtain length
XR R14,R14 * No comapre data required
XR R15,R15 * Length = 0, Pad = X'00'
CLCL R0,R14 * Whole table = X'00' ??
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