ST20-C1 STMICROELECTRONICS [STMicroelectronics], ST20-C1 Datasheet - Page 13

• Manufacturer Part Number: ST20-C1
• Description: Instruction Set Reference Manual
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

2.3.2
In many cases, the action of an instruction depends on the current state of the
processor. In these cases the conditions are shown by an if clause; this can take one
of the following forms:
These conditions can be nested. Braces, {}, are used to group statements which are
dependent on a condition. For example, the cj ( conditional jump ) instruction contains
the following lines:
This says that if the value in Areg is zero, then the jump is taken (the instruction
operand, n, is added to the instruction pointer), otherwise the stack is popped and
execution continues with the next instruction.
2.4
A number of data structures have been defined in this man ual. Each comprises a
number of data slots that are referenced by name in the text and the instruction
descriptions.
These data structures are listed in the tables in Appendix A. Each table gives the
name of each slot in the structure and the word offsets from the base address of the
structure. A slot in a data structure is identified using the offset notation descr ibed in
section 2.2.5:
if (Areg = 0)
else
{
}
Conditions to instructions
if condition
if condition
else
if condition
else if condition
else
Data structures and constants
word[ base_address @ word_offset ]
Iptr
statement
statement
statement
statement
statement
statement
Iptr
Areg
Breg
Creg
next instruction
next instruction + n
Breg
Creg
Areg
2 Notation
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