Against the "generic He" - www - Unnamed repository; edit this file 'description' to name the repository.

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author	1337 h4xx0r <1337.h4xx0r@localhost>	2023-08-01 05:05:02 +0000
committer	1337 h4xx0r <1337.h4xx0r@localhost>	2023-08-01 05:05:02 +0000
commit	eddcd87423a36211d1f44eb09ce443ffe8b31ca7 (patch)
tree	bfa623cd3f22ff4dbe89f8ec4c2a87bce83914b2 /note/pubdom.html
parent	56b813e53d94f49d1c426c97bfebe7c4973ce0af (diff)
download	www-eddcd87423a36211d1f44eb09ce443ffe8b31ca7.tar.gz

Against the "generic He"

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0 files changed, 0 insertions, 0 deletions

kkartik.com> 2018-09-01 20:10:06 -0700 4531 - automatically compute segment addresses' href='/akkartik/mu/commit/subx/examples/ex5.subx?h=hlt&id=a49bc41365bf6b4f0c006c5fbdcb4b519634c42c'>a49bc413 ^

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# Read a character from stdin, save it to a local on the stack, write it to stdout.
#
# To run (from the subx directory):
#   $ ./subx translate examples/ex5.subx -o examples/ex5
#   $ ./subx run examples/ex5

== code
#   instruction                     effective address                                                   register    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

# main:
    # allocate x on the stack
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # subtract from ESP

    # syscall(read, stdin, x, 1)
    # . fd = 0 (stdin)
    bb/copy-to-EBX  0/imm32
    # . data = x (location to write result to)
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              1/r32/ECX   4/disp8         .                 # copy ESP+4 to ECX
    # . size = 1 character
    ba/copy-to-EDX  1/imm32
    # . syscall
    b8/copy-to-EAX  3/imm32/read
    cd/syscall  0x80/imm8

    # syscall(write, stdout, x, 1)
    # . fd = 1 (stdout)
    bb/copy-to-EBX  1/imm32
    # . data = x (location to read from)
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    4/base/ESP  4/index/none              1/r32/ECX   4/disp8         .                 # copy ESP+4 to ECX
    # . size = 1 character
    ba/copy-to-EDX  1/imm32
    # . 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

# . . vim:nowrap:textwidth=0


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