GMS30C2116 Datasheet, PDF (211/322 Pages) Hynix Semiconductor – USERS MANUAL

Appendix A. Instruction Set Details
Do
A-37
DO
Format:
LL format
15
OP-code
1100 1111
87
Ld-code
43
0
Ls-code
Ls-code encoded L0..L15 for Ls
Ld-code encoded L0..L15 for Ld
Notation:
Do xx... Ld, Ls
Description:
The Do instruction is executed as a Software instruction. (The Software instructions causes
a branch to the subprogram associated with each Software instruction.) The associated
subprogram is entered, the stack address other destination operand and one double-word
source operand are passed to it.
The halfword succeeding the Do instruction will be used by the associated subprogram to
differentiate branches to subordinate routines; the associated subprogram must increment
the saved return program counter PC by two.
“xx...” stands for the mnemonic of the differentiating halfword after the OP -code of the Do
instruction.
Operation:
PC := 23 oness // 0 // OP(11..8) // 4 zeros;
(FP + FL)^ := stack address of Ld;
(FP + FL + 1)^ := Ls;
(FP + FL + 2)^ := Lsf;
(FP + FL + 3)^ := old PC(31..1) // old S;
(FP + FL + 4)^ := old SR;
FP := FP + FL, FL := 6;, M := 0;
T := 0; L := 1;
Exceptions:
None