37 lines
1.3 KiB
Plaintext
37 lines
1.3 KiB
Plaintext
## print out a (global variable) string to stdout
|
|
#
|
|
# To run (from the subx directory):
|
|
# $ subx translate examples/ex6.subx -o examples/ex6
|
|
# $ subx run examples/ex6
|
|
# Hello, world!
|
|
|
|
== code
|
|
# instruction effective address operand displacement immediate
|
|
# op subop mod rm32 base index scale r32
|
|
# 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
|
|
|
|
# syscall(write, stdout, X, size)
|
|
# fd = 1 (stdout)
|
|
bb/copy-to-EBX 1/imm32
|
|
# initialize X (location to write result to)
|
|
b9/copy-to-ECX X/imm32
|
|
# initialize size
|
|
8b/copy 0/mod/indirect 5/rm32/.disp32 . . 2/r32/EDX Size/disp32 . # copy *size to EDX
|
|
# syscall
|
|
b8/copy-to-EAX 4/imm32/write
|
|
cd/syscall 0x80/imm8
|
|
|
|
# syscall(exit, EBX)
|
|
b8/copy-to-EAX 1/imm32/exit
|
|
cd/syscall 0x80/imm8
|
|
|
|
== data
|
|
|
|
Size: # size of string
|
|
0e 00 00 00 # 14
|
|
X: # string to print
|
|
48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21 0a 00
|
|
# H e l l o , ␣ w o r l d ! newline null
|
|
|
|
# vim:nowrap:textwidth=0
|