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Instruction Set
4-239
STOS
STOS
Tips
Before using STOS, always be sure to: set up DI with the offset of the string, set up CX
with the length of the string, and use CLD (forward) or STD (backward) to establish the
direction for string processing.
To fill a string with a given value, use the REP prefix to execute STOS repeatedly.
To perform a custom operation on each component in a string, use LODS and STOS within
a loop. Within the loop, use the following sequence of instructions: Use LODS to copy a
component from memory, use other instructions to perform the custom operation, and then
use STOS to copy the component back to memory. To overwrite the original string with the
results, set up DI with the same offset as SI before beginning the loop.
The string instructions always advance SI and/or DI, regardless of the use of the REP prefix.
Be sure to set or clear DF before any string instruction.
Related Instructions
If you want to
See
Process string components from lower to higher addresses
CLD
Copy a component from a port in I/O memory to a string in main memory
INS
Copy a component from a string in memory to a register
LODS
Copy a component from one string in memory to another string in memory
MOVS
Copy a component from a string in main memory to a port in I/O memory
OUTS
Repeat one string instruction
REP
Process string components from higher to lower addresses
STD
Содержание Am186 Series
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