add f_read_next_character

1 files changed, 35 insertions, 23 deletions

diff --git a/bfc.S b/bfc.S
index 44ee7ec..7237ed4 100644
--- a/bfc.S
+++ b/bfc.S
@@ -1,8 +1,6 @@
-.global _start
-
-.data
+.section .constants, "a"
 
-v_elf_header:
+c_elf_header:
 	.byte 0x7f       # Magic Number
 	.ascii "ELF"     #
 	.byte 0x2        # 64-Bit
@@ -24,9 +22,11 @@ v_elf_header:
 	.hword 0x3       # TODO: Number Of Entries in Section Header Table
 	.hword 0x2       # TODO: Index of Section Header Table Entry containing section names
 
-v_usage_message:
+c_usage_message:
 	.asciz "bfc [input file] [output file]\n"
 
+.section .variables, "aw"
+
 v_input_fd:
 	.int 0x0
 
@@ -42,33 +42,30 @@ v_buffer_end:
 v_buffer_cursor:
 	.quad 0x0
 
+v_input_char:
+	.byte 0x0
 
-.text
+
+.section .code, "ax"
+.global _start
 _start:
 	mov %rsp, %rbp
 	call f_check_args
 	call f_open_files
 	call f_init_buffer
 
-	mov $v_buffer_cursor, %rbx
-	mov (%rbx), %rsi
-	add $0x300, %rsi
-	mov %rsi, (%rbx)
-	call f_check_buffer
-
-	mov $v_buffer_cursor, %rsi
-	mov (%rbx), %rsi
-	add $0x300, %rsi
-	mov %rsi, (%rbx)
-	call f_check_buffer
-
-	# ----
+l_read_loop:
+	call f_read_next_character
+	cmp $0, %rax
+	je l_read_loop_end
 
 	mov $1, %rax
-	mov %rcx, %rdi
-	mov $v_elf_header, %rsi
-	mov $0x40, %rdx
+	mov $1, %rdi
+	mov $v_input_char, %rsi
+	mov $1, %rdx
 	syscall
+	jmp l_read_loop
+l_read_loop_end:
 
 	# ----
 
@@ -76,10 +73,12 @@ _start:
 	mov $0, %rdi
 	jmp f_exit
 
+
 f_exit:
 	mov $60, %rax
 	syscall
 
+
 f_check_args:
 	mov (%rbp), %rax
 	cmp $3, %rax
@@ -87,7 +86,7 @@ f_check_args:
 
 	mov $1, %rax
 	mov $2, %rdi
-	mov $v_usage_message, %rsi
+	mov $c_usage_message, %rsi
 	mov $32, %rdx
 	syscall
 
@@ -97,6 +96,7 @@ f_check_args:
 l_check_args_success:
 	ret
 
+
 f_open_files:
 	mov $2, %rax
 	mov 16(%rbp), %rdi
@@ -115,6 +115,7 @@ f_open_files:
 	mov %eax, (%rbx)
 	ret
 
+
 f_close_files:
 	mov $3, %rax
 	mov %rbx, %rsi
@@ -125,6 +126,7 @@ f_close_files:
 	syscall
 	ret
 
+
 f_init_buffer:
 	mov $12, %rax
 	mov $0, %rdi
@@ -157,3 +159,13 @@ f_check_buffer:
 	call f_resize_buffer
 l_check_buffer_large_enough:
 	ret
+
+
+f_read_next_character:
+	mov $0, %rax
+	mov $v_input_fd, %rbx
+	mov (%rbx), %rdi
+	mov $v_input_char, %rsi
+	mov $1, %rdx
+	syscall
+	ret