Add hex

src/int_to_string.asm

@@ -15,6 +15,8 @@ cmp r4, 2
 je bin
 cmp r4, 8
 je oct
+cmp r4, 16
+je hex
 mov flags, errno.INTTOSTR_BAD_BASE
 jmp r13
 
@@ -110,3 +112,47 @@ lsr r5, r1, r4          ; Select bit and advance counter
 and r5, r5, 7
 sub r4, r4, 3
 jmp oct_print
+
+; Convert integer to hexadecimal string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4 - input counter
+; r5 - character
+pub hex:
+mov r4, 28
+
+hex_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+
+cmp r4, 0               ; Start printing if last bit ...
+jl hex_print
+cmp r5, zr              ; .. or if nonzero
+je hex_find_one
+
+lsr flags, r5, 2        ; Check buffer size
+add flags, flags, 3
+cmp flags, r3
+ja badbuffer
+
+hex_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+cmp r5, 0x39 ; '9'
+jle hex_no_letter
+add r5, r5, 0x07 ; 'A' - '0' - 10
+hex_no_letter:
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, 0               ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+jmp hex_print