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| -rw-r--r-- | docs/re/rep_prefix.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/docs/re/rep_prefix.txt b/docs/re/rep_prefix.txt new file mode 100644 index 0000000..b1206cc --- /dev/null +++ b/docs/re/rep_prefix.txt @@ -0,0 +1,18 @@ +The "rep" prefix on a string instruction repeats that string instruction for CX block loads. +e.g. +STOS is "Store String" +It will store the value in AX at the address in RDI +(technically, STOSB, STOSW, STOD, and STOSQ use AL, AX, EAX, and RAX respectively) +If RCX = 0x20, RDI = some buffer, and RAX = 0, + +`rep stosq` + +is equivalent to: + +``` +buf_ptr = buf +for(i = 0x20; i != 0; i++) + *buf_ptr = 0; + buf_ptr++; +``` + |