draftng

8 files changed, 235 insertions, 9 deletions

diff --git a/Makefile b/Makefile
index 69beadf..05f6c5f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 PROGNAME=$(shell pwd | xargs basename)
 
-$(PROGNAME): main.o
-	ld -o $@ $<
+$(PROGNAME): main.o printf.o string.o
+	ld -o $@ $^
 
 %.o: %.s syscall.s
 	as -o $@ $<
diff --git a/backup.s b/backup.s
new file mode 100644
index 0000000..10f9fb5
--- /dev/null
+++ b/backup.s
@@ -0,0 +1,32 @@
+.ifndef __BACKUP__
+.set __BACKUP__, 1
+
+.macro __backup_next n, args:vararg
+.ifnb \args
+	__backup\n \args
+.endif
+.endm
+
+.macro __backup4 arg:req, args:vararg
+	pushq \arg
+.ifnb \args
+.error "backup: too many arguments"
+.endif
+.endm
+
+.macro __backup3 arg:req, args:vararg
+	pushq \arg
+	__backup_next 4, \args
+.endm
+
+.macro __backup2 arg:req, args:vararg
+	pushq \arg
+	__backup_next 3, \args
+.endm
+
+.macro backup arg:req, args:vararg
+	pushq \arg
+	__backup_next 2, \args
+.endm
+
+.endif
diff --git a/lib.s b/lib.s
new file mode 100644
index 0000000..1397b90
--- /dev/null
+++ b/lib.s
@@ -0,0 +1,17 @@
+.ifndef __LIB__
+.set __LIB__, 1
+
+.include "restore.s"
+.include "backup.s"
+.include "sys.s"
+
+.macro prologue
+	pushq %rbp
+	movq %rsp, %rbp
+.endm
+
+.set STDIN,	0
+.set STDOUT,	1
+.set STDERR,	2
+
+.endif
diff --git a/main.s b/main.s
index aa1f293..7bc2b73 100644
--- a/main.s
+++ b/main.s
@@ -2,9 +2,17 @@
 
 .globl _start
 _start:
-	sys write, $STDOUT, $msg, $len
+	movq %rsp, %rbp
+
+	pushq $-1024
+	pushq $-1024
+	pushq $msg
+	pushq $fmt
+	call printf
+
 	sys exit, $0
 
 .data
-msg:	.ascii "Hello, World!\n"
-len = .-msg
+fmt:	.asciz "%s and %d and %u\n"
+msg:	.asciz "Hello, World"
+bye:	.asciz "bye!"
diff --git a/printf.s b/printf.s
new file mode 100644
index 0000000..3bb24ca
--- /dev/null
+++ b/printf.s
@@ -0,0 +1,120 @@
+.include "lib.s"
+
+.macro bufpush
+	cmpq $bufend, %rdi
+	jle 9f
+	stosb
+	9:
+.endm
+
+.globl printf
+printf:
+	prologue
+
+	backup %rax, %rbx, %rcx, %rdx
+	backup %rsi, %rdi
+
+	movq 16(%rbp), %rsi
+	leaq 24(%rbp), %rbx
+	movq $buf, %rdi
+
+.loop:
+	lodsb
+	testb %al, %al
+	jz .loopout
+
+	cmpb $'%, %al
+	jne .append
+
+	lodsb
+	testb %al, %al
+	jz .loopout
+
+	cmpb $'%, %al
+	je .append
+
+	cmpb $'s, %al
+	je .print_string
+
+	cmpb $'d, %al
+	je .print_signed
+
+	cmpb $'u, %al
+	je .print_unsigned
+
+	jmp .loop
+
+.append:
+	bufpush
+	jmp .loop
+
+.print_string:
+	backup %rsi
+
+	movq (%rbx), %rsi
+	addq $8, %rbx
+	jmp 2f
+
+	1: bufpush 
+	2: lodsb
+	testb %al, %al
+	jnz 1b
+
+	restore %rsi
+	jmp .loop
+
+.print_signed:
+	movq (%rbx), %rax
+	addq $8, %rbx
+
+	cmpq $0, %rax
+	jge 1f
+
+	pushq %rax
+	movb $'-, %al
+	bufpush
+	popq %rax
+	negq %rax
+
+	1:
+	movq $10, %rcx
+	call .print_number
+	jmp .loop
+
+.print_unsigned:
+	movq (%rbx), %rax
+	addq $8, %rbx
+
+	movq $10, %rcx
+	call .print_number
+	jmp .loop
+
+.print_number:
+	xorq %rdx, %rdx
+	divq %rcx
+	pushq %rdx
+	testq %rax, %rax
+	jz 1f
+	call .print_number
+	1:
+	popq %rax
+	addq $'0, %rax
+	bufpush
+	ret
+
+.loopout:
+	movq %rdi, %rdx
+	subq $buf, %rdx
+	movq $buf, %rsi
+	movq $STDOUT, %rdi
+	sys write
+
+	restore %rsi, %rdi
+	restore %rax, %rbx, %rcx, %rdx
+
+	leave
+	ret
+
+.bss
+.comm buf, 4096
+.comm bufend, 2
diff --git a/restore.s b/restore.s
new file mode 100644
index 0000000..da1ec03
--- /dev/null
+++ b/restore.s
@@ -0,0 +1,32 @@
+.ifndef __RESTORE__
+.set __RESTORE__, 1
+
+.macro __restore_next n, args:vararg
+.ifnb \args
+	__restore\n \args
+.endif
+.endm
+
+.macro __restore4 arg:req, args:vararg
+.ifnb \args
+.error "restore: too many arguments"
+.endif
+	popq \arg
+.endm
+
+.macro __restore3 arg:req, args:vararg
+	__restore_next 4, \args
+	popq \arg
+.endm
+
+.macro __restore2 arg:req, args:vararg
+	__restore_next 3, \args
+	popq \arg
+.endm
+
+.macro restore arg:req, args:vararg
+	__restore_next 2, \args
+	popq \arg
+.endm
+
+.endif
diff --git a/string.s b/string.s
new file mode 100644
index 0000000..b6bc317
--- /dev/null
+++ b/string.s
@@ -0,0 +1,21 @@
+.include "lib.s"
+
+.globl strlen
+strlen:
+	prologue
+
+	backup %rdi, %rcx
+
+	movq 16(%rbp), %rdi
+	xorq %rax, %rax
+	movq $-1, %rcx
+
+	repne scasb
+
+	movq $-2, %rax
+	subq %rcx, %rax
+
+	restore %rdi, %rcx
+
+	leave
+	ret
diff --git a/sys.s b/sys.s
index 2a76e09..b2d002e 100644
--- a/sys.s
+++ b/sys.s
@@ -62,8 +62,4 @@
 	syscall
 .endm
 
-.set STDIN,	0
-.set STDOUT,	1
-.set STDERR,	2
-
 .endif