diff options
| -rw-r--r-- | b32e.asm | 27 |
1 files changed, 21 insertions, 6 deletions
@@ -38,11 +38,18 @@ write_output: ; b32e ; encodes 40 bits (5 bytes) to 8 RFC4648 base32 characters -; uses reg: rbx, r11 +; uses reg: rax(in: bytes read), rbx, rcx, r11 ; uses mem: input_buffer, output_buffer b32e: + ; save the number of bits read in cl + mov bl, 8 ; each byte contains 8 bits + mul bl + mov cl, al ; set up output counter xor r11, r11 + ; initialize output buffer with padding + mov rbx, 0x3d3d3d3d3d3d3d3d + mov qword [output_buffer], rbx .loop: ; clear rbx @@ -66,12 +73,20 @@ b32e: ; increase counter inc r11 + ; check number of bits converted >= bits read + mov bl, 5 ; each iteration processed 5 bits + mov rax, r11 + mul bl + cmp al, cl + jge .exit + ; check counter ; when the counter reaches 8 it means that 8 characters (40 bits) ; have been processed and written cmp r11, 8 - js .loop + jl .loop +.exit: ret @@ -86,11 +101,11 @@ _start: je .exit ; swap endianness of input - mov rax, qword [input_buffer] - bswap rax + mov rbx, qword [input_buffer] + bswap rbx ; correct position in qword - shr rax, 24 - mov qword [input_buffer], rax + shr rbx, 24 + mov qword [input_buffer], rbx ; convert to base 32 call b32e |