Zilog Z8F0130 - Manual (Page 341)

UM013037-1212 Structured Assembly
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modified name if the result matches a name created by the .STRUCT , .UNION , or .TAG
directives.
The .WITH directives can be nested, in which case the search is from the deepest level of
nesting outward. In the event that multiple names are found, a warning is generated and
the first such name is used.
If name is specified with the .ENDWITH directive, the name must match that used for the
.WITH directive. The intent is to allow for code readability with some checking by the
assembler.
To provide an example, examine the COMPUTE_PAY routine below.
COMPUTE_PAY:

; Enter with pointer to an EMPLOYEE in R2, days in R1

; Return with pay in R0,R1
LD R0,EMPLOYEE.SALARY(R2)

MULT RR0

RET
The above routine could be rewritten using the .WITH directive as:
COMPUTE_PAY:

; Enter with pointer to an EMPLOYEE in R2, days in R1

; Return with pay in R0,R1
.WITH EMPLOYEE

LD R0, SALARY(R2)

MULT RR0

RET

.ENDWITH EMPLOYEE
Structured Assembly
Structured assembly supports execution-time selection of sequences of source statements
based on execution-time conditions. The structured assembly directives test for a specified
condition and execute a block of statements only if the condition is true.
The structured assembly directives, when used in conjunction with the ability to assembly
and link modules independently, facilitate structured programming in assembly language.
It can be difficult to assimilate the logical structure of a traditional, nonstructured assem-
bly language program. Structured assembly language programs are generally easier to read
and understand than nonstructured programs. They might also be easier to debug and
change. The following sections describe structured assembly: