avr: added HexByteToAscii, HexWordToAscii

avr/common/itoa.asm

@@ -90,6 +90,92 @@ IntToAscii_ret:
 
 
 
+; ---------------------------------------------------------------------------
+; @routine HexWordToAscii @global
+;
+; Shares buffer with @ref IntToAscii !
+;
+; @param R21:R20 value to transform to ascii
+; @return X      pointer to result string (will be overwritten by next call!)
+; @clobbers R16, R17
+
+HexWordToAscii:
+  ldi xl, LOW(itoa_buffer)
+  ldi xh, HIGH(itoa_buffer)
+  mov r16, r21
+  rcall writeHexByteToBuffer  ; write hi byte
+  mov r16, r20
+  rcall writeHexByteToBuffer  ; write low byte
+  clr r16
+  st X+, r16
+  sbiw xh:xl, 5
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine HexByteToAscii @global
+;
+; Shares buffer with @ref IntToAscii !
+;
+; @param R16 value to transform to ascii
+; @return X      pointer to result string (will be overwritten by next call!)
+; @clobbers R16, R17
+
+HexByteToAscii:
+  ldi xl, LOW(itoa_buffer)
+  ldi xh, HIGH(itoa_buffer)
+  rcall writeHexByteToBuffer
+  clr r16
+  st X+, r16
+  sbiw xh:xl, 3
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine writeHexByteToBuffer
+;
+; @param R16 value to transform to ascii
+; @param X      pointer to current pos in result buffer
+; @clobbers R16, R17
+
+writeHexByteToBuffer:
+  push r16
+    swap r16
+    rcall hexNibbleToAscii ; transform high nibble (r16, r17)
+    st X+, r16
+  pop r16
+  rcall hexNibbleToAscii   ; transform low nibble (r16, r17)
+  st X+, r16
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine hexNibbleToAscii
+;
+; Convert a nibble to an ASCII char.
+; @return R16 ASCII representation of that nibble (e.g. '0' for 0)
+; @param  R16 byte (in bits 0-3)
+; @clobbers r16, r17
+
+hexNibbleToAscii:
+  andi r16, 0xf
+  cpi r16, 10
+  brcs hexNibbleToAscii_l1
+  ldi r17, 7
+  add r16, r17
+hexNibbleToAscii_l1:
+  ldi r17, '0'
+  add r16, r17
+  ret
+; @end
+
+
 
 #endif