*
*   Hex Math routine for Solos monitor
*
*   Syntax:  HM  value1  value2
*            Values can be anything from 0 to FFFFH
*            Only legal Hex permitted.  Overflow or
*            underflow is ignored.  Both values must
*            be present.
*
*   Subroutine addresses within Solos monitor
*
SOUT  EQU  0C019H  Output a character from B
SCONV  EQU  0C33AH  Get a 16 bit value to HL
ADOUT  EQU  0C3E8H  Output a 16 bit value from HL
NLOOP  EQU  0C56AH  Output a string pointed to by HL
*
CUTAB  ORG  0C83CH  Custom command table entry
*
 ASC  'HM'  Command syntax
 DW  HMATH
 DB  0  End of table mark
*
HMATH  ORG  0C900H  Hex Math routine address
*
 CALL  SCONV  Get value1, abort if missing
 PUSH  H  Save it
 CALL  SCONV  Get value2, abort if missing
 PUSH  H  Save it
 LXI  H,MSG  Point to format string
 MVI  D,6  String counter
 CALL  NLOOP  Send it out
 POP  D  Get value2 to DE
 POP  H  Get value1 to HL
 PUSH  H  Save value1 again
 PUSH D  Save value2 again
 DAD  D  Add DE to HL
 CALL  ADOUT  Send out the result
 POP D  Get value2 back to DE
 POP  H  Get value1 back to HL
*
 MOV  A,D  Now get two's complement
 CMA  .  of DE to find difference
 MOV  D,A
 MOV  A,E
 CMA  .
 MOV  E,A
 INX  D
*
 DAD  D  Add it to HL
 MVI  B,'-'  Send out minus sign
 CALL  SOUT
 JMP  ADOUT  Send out minus result
*
MSG:  ASC  '  =  +'
*
 END
*