FEAT 32 and 64-bit SYS_WRITE calls, one by length, the other with strlen.
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20
Makefile
20
Makefile
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@ -1,12 +1,24 @@
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help: ## Print this help message
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@M=$$(perl -ne 'm/^((\w|-)*):.*##/ && print length($$1)."\n"' Makefile | \
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sort -nr | head -1) && \
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perl -ne "m/^((\w|-)*):.*##\s*(.*)/ && print(sprintf(\"%s: %s\t%s\n\", \$$1, \" \"x($$M-length(\$$1)), \$$3))" Makefile
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hello32:
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hello32: hello32.s ## Build the 32 bit version of Project 1
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nasm -f elf hello32.s
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ld -m elf_i386 -o hello32 hello32.o
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hello64:
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hello64: hello64.s ## Build the 32 bit version of Project 1
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nasm -f elf64 hello64.s
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ld -o hello64 hello64.o
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clean:
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rm -f hello32 hello64 *.o
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hello-strlen32: hello-strlen32.s ## Build the 32 bit version of Project 1
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nasm -f elf hello-strlen32.s
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ld -m elf_i386 -o hello-strlen32 hello-strlen32.o
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hello-strlen64: hello-strlen64.s ## Build the 32 bit version of Project 1
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nasm -f elf64 hello-strlen64.s
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ld -o hello-strlen64 hello-strlen64.o
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clean: ## Delete all built and intermediate features
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rm -f hello32 hello64 hello-strlen32 hello-strlen64 *.o
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@ -0,0 +1,47 @@
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;; Hello World Program #1
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;; Compile with: nasm -f elf hello.s
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;; Link with: ld -m elf_i386 -o hello hello.o
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;; Run with: ./hello
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;; sys/unistd_32.h
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%define SYS_write 4
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%define SYS_exit 1
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;; unistd.h
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%define STDOUT 1
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section .data
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msg db "Hello You Beautiful Human, You're Looking Fine Today!", 0Ah, 00h
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section .text
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global _start
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_start:
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mov ebx, msg ; Move the address of the message into ebx
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mov eax, ebx ; Move the address of the message into eax (Register-to-register copying is faster that a constant!)
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nextchar:
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cmp byte [eax], 0 ; Compare the byte pointed to by eax with zero.
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;; Small detail: cmp and sub use the same internal architecture,
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;; except cmp doesn't copy the results into the first operand and
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;; sub does. cmp sets flags; does sub? This is why 'jz' works,
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;; because if they're equal the result of subtraction is zero.
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jz counted ; Jump if the zero flag set
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inc eax
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jmp nextchar
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counted:
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sub eax, ebx ; Subtract the end from the start, and the result goes into the start
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mov edx, eax ; syswrite needs that register for something else! Man, picking registers is hard.
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mov ecx, msg ; Address of the message (not the content)
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mov ebx, STDOUT ; using STDOUT (see definition above)
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mov eax, SYS_write ; Using WRITE in 32-bit mode?
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int 80h ; Interrupt target. The 'h' means 'hexidecimal'
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mov ebx, 0
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mov eax, SYS_exit
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int 80h
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;; Hello World Program #1
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;; Compile with: nasm -f elf64 hello.s
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;; Link with: ld -o hello hello.o
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;; Run with: ./hello
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;; sys/unistd_64.h
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%define SYS_write 1
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%define SYS_exit 60
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;; unistd.h
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%define STDOUT 1
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section .data
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msg db "Hello You Beautiful Human, You're Looking Mighty Fine!", 0Ah, 00h
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section .text
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global _start
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_start:
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mov rsi, msg ; Move the address of the message into rsi
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mov rax, rsi ; Move the address of the message into rax
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; (Register-to-register copying is faster that a constant!)
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nextchar:
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cmp byte [rax], 0 ; Compare the byte pointed to by eax with zero
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;; Small detail: cmp and sub use the same internal architecture,
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;; except cmp doesn't copy the results into the first operand and
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;; sub does. cmp sets flags; does sub? This is why 'jz' works,
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;; because if they're equal the result of subtraction is zero.
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jz counted ; Jump if the zero flag set
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inc rax
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jmp nextchar
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counted:
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sub rax, rsi ; Substract source from endpointer, leaving counter
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mov rdx, rax ; Length of the message
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mov rsi, msg ; Address of the message
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mov rdi, STDOUT ; using STDOUT (see definition above)
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mov rax, SYS_write ; Using WRITE in 32-bit mode?
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syscall
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mov rdi, 0
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mov rax, SYS_exit
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syscall
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@ -1,5 +1,5 @@
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;; Hello World Program #1
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;; Compile with: nasm -f elf32 hello.s
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;; Compile with: nasm -f elf hello.s
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;; Link with: ld -m elf_i386 -o hello hello.o
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;; Run with: ./hello
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@ -12,12 +12,13 @@
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section .data
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msg db "Hello You Beautiful Human", 0Ah
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len equ $-msg ; NASM-supplied macro
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section .text
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global _start
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_start:
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mov edx, 26d ; Length of the message. The 'd' means 'decimal'
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mov edx, len
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mov ecx, msg ; Address of the message (not the content)
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mov ebx, STDOUT ; using STDOUT (see definition above)
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mov eax, SYS_write ; Using WRITE in 32-bit mode?
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@ -1,6 +1,6 @@
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;; Hello World Program #1
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;; Compile with: nasm -f elf32 hello.s
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;; Link with: ld -m elf_i386 -o hello hello.o
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;; Compile with: nasm -f elf64 hello.s
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;; Link with: ld -o hello hello.o
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;; Run with: ./hello
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;; sys/unistd_64.h
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@ -12,12 +12,13 @@
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section .data
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msg db "Hello You Beautiful Human", 0Ah
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len equ $-msg ; NASM-supplied macro
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section .text
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global _start
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_start:
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mov rdx, 26d ; Length of the message
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mov rdx, len ; Length of the message
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mov rsi, msg ; Address of the message
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mov rdi, STDOUT ; using STDOUT (see definition above)
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mov rax, SYS_write ; Using WRITE in 32-bit mode?
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