Use 4 spaces for indent, update comments, change input buffer shift direction

1 files changed, 56 insertions, 43 deletions

diff --git a/b32e.asm b/b32e.asm
index ada7ff0..9c136dd 100644
--- a/b32e.asm
+++ b/b32e.asm
@@ -12,63 +12,76 @@ global _start
 
 ; read_input
 ; reads 5 bytes (40 bits) of input
+; uses reg: rax, rdi, rsi, rdx
+; uses mem: input_buffer
 read_input:
-	; linux x64 read(stdin, input_buffer, 5)
-	mov rax, 0
-	mov rdi, 0
-	mov rsi, input_buffer
-	mov rdx, 5
-	syscall
-	ret
+    ; linux x64 read(stdin, input_buffer, 5)
+    mov rax, 0
+    mov rdi, 0
+    mov rsi, input_buffer
+    mov rdx, 5
+    syscall
+    ret
 
 ; write_output
 ; writes the output buffer to stdout
+; uses reg: rax, rdi, rsi, rdx
+; uses mem: output_buffer(ro)
 write_output:
-	; linux x64 write(stdout, output_buffer, 8)
-	mov rax, 1
-	mov rdi, 1
-	mov rsi, output_buffer
-	mov rdx, 5
-	syscall
-	ret
+    ; linux x64 write(stdout, output_buffer, 8)
+    mov rax, 1
+    mov rdi, 1
+    mov rsi, output_buffer
+    mov rdx, 5
+    syscall
+    ret
 
 ; b32e
 ; encodes 40 bits (5 bytes) to 8 RFC4648 base32 characters
-; inputs: bl=5 bits
-; uses: rxb, rdx, r11
+; uses reg: rbx, rdx, r11
+; uses mem: input_buffer, output_buffer
 b32e:
-	; set up outputs counter
-	xor r11, r11
+    ; set up output counter
+    xor r11, r11
+
 .loop:
-	; get 5 bits from the input
-	xor rbx, rbx
-	mov bl, byte [input_buffer]
-	; mask and shift to convert to a number 0 ~ 32
-	and bl, 0xf8
-	shr bl, 3
+    ; clear rbx
+    xor rbx, rbx
+
+    ; get a byte from the input
+    mov bl, byte [input_buffer]
+
+    ; mask and shift to get 5 bits which is a number in 0 ~ 31
+    and bl, 0xf8
+    shr bl, 3
+
+    ; rshift the input buffer
+    shr qword [input_buffer], 5
+
+    ; convert to base32
+    add rbx, rfc4648
+    mov dl, byte [rbx]
+    mov [output_buffer + r11], dl 
 
-	; rshift the input buffer
-	shl qword [input_buffer], 5
+    ; increase counter
+    inc r11
 
-	; convert to base32
-	add rbx, rfc4648
-	mov dl, byte [rbx]
-	mov byte [output_buffer + r11], dl 
+    ; check counter
+    ; when the counter reaches 8 it means that 8 characters (40 bits)
+    ; have been processed and written
+    cmp r11, 8
+    js .loop 
 
-	; increase counter
-	inc r11
-	cmp r11, 8
-	js .loop 
-	ret
+    ret
 
 
 _start:
-	nop
-	call read_input
-	call b32e
-	call write_output
+    nop
+    call read_input
+    call b32e
+    call write_output
 .exit:
-	; linux x64 exit(0)
-	mov rax, 60
-	mov rdi, 0
-	syscall
+    ; linux x64 exit(0)
+    mov rax, 60
+    mov rdi, 0
+    syscall