NonStop S-Series Server Description Manual (G06.24+)

TNS Instruction Set
HP NonStop S-Series Server Description Manual—520331-003
11-34
Definitions of TNS Instructions
POP (124nrc). Pop Data Space to Registers. This instruction loads the register stack
with the top elements of the data stack (as indicated by the current S register setting).
The “n” field of the instruction indicates the value RP will have following the instruction,
the “r” field specifies the last register stack element to be loaded from memory, and the
“c” field specifies the number of registers minus one that will be loaded. If the resultant
value of S is greater than 32767, a stack overflow trap occurs. Figure 11-11 on
page 11-35 illustrates the bit fields and the action of the POP instruction. For binary
coding details, refer to Table B-3 on page B-3.
PUSH (024nrc). Push Registers to Data Space. This instruction transfers the contents
of a specified number of elements in the register stack to the top of the data stack in
memory. The “n” field of the instruction is the value to which RP will be set following
the instruction, the “r” field specifies the last register stack element to be pushed, and
the “c” field is the number of registers minus one that will be pushed to memory.
Following the PUSH instruction, the S register points to the last element pushed onto
the memory stack. If the resultant value of S is greater than 32767, a stack overflow
trap occurs. Figure 11-11 on page 11-35 illustrates the bit fields and the action of the
PUSH instruction. For binary coding details, refer to Table B-3 on page B-3.
In Figure 11-11, the PUSH instruction transfers the contents of six registers of the
register stack to the data stack in memory. The POP instruction does the reverse.