stdio example added

x86_64/1_stdio.asm

@@ -0,0 +1,51 @@
+global _start
+
+section .data
+  str: db "Please give me a string: " ; \n = 0xA
+
+  strSize: equ $ - str
+  ; $ = current assembler address.
+  ; Since str is all that is above it must be the size
+
+  stdin: equ 0 ; POSIX
+  stdout: equ 1 ; POSIX
+
+; Uninitialized space goes here, pretty much your heap of uninitialized bytes
+; for all kinds of purposes
+section .bss
+  strBuffer: resb 64 ; reserve 64 bytes
+  strBufferSize: equ 64 ; same as above
+
+; This is where the code goes. Text. Makes sense, right?
+section .text
+_start:
+  ; x64 has the syscall function, in contrast to int in x86 and ARM
+
+  ; Write to stdout
+  mov rax, 1
+  mov rdi, stdout  ; fd to write to
+  mov rsi, str     ; pointer
+  mov rdx, strSize ; size
+  syscall ; all arguments are specified above! (x86 = int 0x80)
+
+  ; Read from stdin
+  xor rax, rax ; 0
+  mov rdi, stdin     ; fd to read from
+  mov rsi, strBuffer ; where to store it
+  mov rdx, strBufferSize ; maximum number of bytes
+  syscall
+
+  ; syscall return codes are always stored in register A
+  ; The number of bytes read in was returned through this
+	mov rdx, rax
+
+	mov rax, 1
+	mov rdi, stdout
+	mov rsi, strBuffer
+	syscall
+
+
+  ; Exit routine
+  mov rax, 60 ; 60 is the exit routine
+  xor rdi, rdi ; our return code (0)
+  syscall

x86_64/makefile

@@ -2,13 +2,19 @@ CC = gcc
 AS = nasm
 LD = ld
 
+ASSEMBLIES = $(wildcard *.asm)
+PROGRAMS = $(patsubst %.asm, bin/%, $(ASSEMBLIES))
+
 .PHONY: all clean
 
-all: build 0_basic
+all: bin build $(PROGRAMS)
 
 clean:
 	-rm -r build
-	-rm 0_basic
+	-rm -r bin
+
+bin:
+	mkdir bin
 
 build:
 	mkdir build
@@ -16,6 +22,5 @@ build:
 build/%.o: %.asm
 	$(AS) -g -f elf64 $< -o $@
 
-0_basic: build/0_basic.o
+bin/%: build/%.o
 	$(LD) $< -o $@
-