Miscalleneous routines II
THE 'FLASH BORDER' SUBROUTINE
When +D system variable RBCC (address @0) doesn't hold zero, this subroutine flashes the
border. The border colour is then obtained by masking the E register (holds sectornumber)
1684 FLASH_BORD LD A,(#2000) Fetch RBCC.
1687 AND E Incorporate sectornumber.
1688 RET Z Return if 'no flashing'.
1689 AND #07 Keep border colour only.
168B OUT (254),A Set the border and finished.
THE 'BORDER COLOUR RESTORE' SUBROUTINE
This subroutine is used whenever the border colour was changed during an I/O operation,
and needs to be restored to its original state.
168E BORD_REST PUSH AF
168F LD A,(23624) Fetch lower screen attribute (BORDCR).
1692 AND #38 Only the border bits.
1694 RRCA Move the bits to 0-2.
1697 OUT (254),A Restore colour.
1699 POP AF
THE 'PRINT DIRECTORY DESCR.' SUBROUTINE
This subroutine is used to print the directory description of a file during an 'extended
CAT' command. On entry the A register holds the directory description.
169B PRT_TYPE PUSH AF
169C LD HL,#16E9,TYPE_TABLE Start of messages table.
169F LD BC,85 Length of table excluding 'WHAT?'.
16A2 CPIR Make HL point to right message. HL
points to 'WHAT?' with unknown types.
16A4 CALL #18B8,PRT_MSG_HL Print the message.
16A7 POP AF Restore file type.
16A8 CP 1
16AA JR NZ,#16C1,PRT_NOBAS Jump with no 'BASIC' files.
16AC LD (IX+13),219 Make RPT point to autostart line high.
16B0 CALL #0D97,RPT_HL1 HL points to it now.
16B3 LD A,(HL)
16B4 AND 192
16B6 JR NZ,#16E4,PRT_EXIT Jump if no autostart line present.
16B8 LD D,(HL) Otherwise fetch it.
16B9 DEC HL
16BA LD E,(HL)
16BB EX DE,HL
16BC CALL #1744,PRT_NUM Print it.
16BF JR #16E4,PRT_EXIT
Now the other directory descriptions are handled.
16C1 PRT_NOBAS CP 4
16C3 JR NZ,#16E4,PRT_EXIT Jump with no 'CODE' files.
16C5 LD (IX+13),215 RPT points to file address high byte.
16C9 CALL #0D97,RPT_HL1 Make HL hold RPT.
16CC LD D,(HL) Fetch file address.
16CD DEC HL
16CE LD E,(HL)
16CF EX DE,HL
16D0 PUSH DE
16D1 CALL #1744,PRT_NUM Print file address.
16D4 LD A,44 Print a ','.
16D6 CALL #1799,PRT_A
16D9 POP HL
16DA DEC HL
16DB LD D,(HL) Fetch file length.
16DC DEC HL
16DD LD E,(HL)
16DE EX DE,HL
16DF LD A,0 Ignore leading zero's.
16E1 CALL #1746,PRT_N10000 Print the length.
16E4 PRT_EXIT LD A,13 Print a NEWLINE and exit.
16E6 JP #1799,PRT_A
THE 'DIRECTORY DESCRIPTION' TABLE
This table contains the directory description messages as printed with an 'extended
CAT'. Each message is preceeded by is description value.
16E9 TYPE_TABLE DEFB 1
16EA DEFM "BAS "
16EE DEFB 2
16EF DEFM "D.ARRAY"
16F6 DEFB 3
16F7 DEFM "$.ARRAY"
16FE DEFB 4
16FF DEFM "CDE "
1703 DEFB 5
1704 DEFM "SNP 48k"
170B DEFB 6
170C DEFM "MD.FILE"
1713 DEFB 7
1714 DEFM "SCREEN$"
171B DEFB 8
171C DEFM "SPECIAL"
1723 DEFB 9
1724 DEFM "SNP 128k"
172C DEFB 10
172D DEFM "OPENTYPE"
1735 DEFB 11
1736 DEFM "EXECUTE"
173D DEFB 12
173E DEFM "WHAT?"
1743 DEFB 0
THE 'PRINT NUMBER' SUBROUTINE
This subroutine prints the number held in the HL register. Entering the routine at #1744
prints leading spaces, while the other entry points prints the character held in the A
register in place of leading zero's. A value of 0 means don't print anything.
1744 PRT_NUM LD A,32 Spaces are printed in place of leading
1746 LD DE,10000 Start printing with tens-of-thousands.
1749 CALL #1763,PRT_DIGIT
174C PRT_N1000 LD DE,1000 Start printing with thousands.
174F CALL #1763,PRT_DIGIT
1752 PRT_N100 LD DE,100 Start printing with hundreds.
1755 CALL #1763,PRT_DIGIT
1758 PRT_N10 LD DE,10 Start printing with tens.
175B CALL #1763,PRT_DIGIT
175E LD A,L Print units.
175F ADD A,"0" Add ASCII offset for digits.
1761 JR #1799,PRT_A
THE 'PRINT DIGIT' SUBROUTINE
This subroutine is used to print a digit, the HL register holds the number and the DE
register the value for 'repeated subtraction'.
1763 PRT_DIGIT PUSH AF Preserve leading character.
1764 XOR A Clear Carry and counter.
1765 PRT_DIG1 SBC HL,DE The 'trial' subtraction.
1767 JR C,#176C,PRT_DIG2 Jump if exhausted.
1769 INC A Count each trial.
176A JR #1765,PRT_DIG1 Jump back for next try.
The A register now holds the digit to be printed.
176C PRT_DIG2 ADD HL,DE Restore last subtraction.
176D AND A
176E JR NZ,#1775,PRT_DIG3 Jump if a non zero value is to be
1770 POP DE Retrieve the leading character into D.
1771 ADD A,D Add it to zero.
1772 RET Z Return if nothing has to be printed.
1773 JR #1799,PRT_A Otherwise print the leading character.
Now print the digit.
1775 PRT_DIG3 ADD A,"0" Add ASCII offset for digits.
1777 CALL #1799,PRT_A Print the digit.
177A POP DE Balance the stack.
177B LD A,"0" All zeroes after any non zero digit
177D RET will be printed as '0'.
THE 'PRINT OUT MESSAGE' SUBROUTINE
This subroutine handles the printing of messages directly following the 'CALL'
instruction to this routine. When the +D's own error stack pointer (D_ERR_SP) holds a
non-zero value, i.e during hook and command codes, no printing has to take place. The
carry flag is set and the A register then holds 32, signalling 'error during hook/command
code execution' as usual.
177E PO_MSG LD HL,(#2066) Fetch (D_ERR_SP).
1781 LD A,H
1782 OR L
1783 JR Z,#178A,PO_MSG1 Jump if it isn't used.
1785 LD SP,HL Clear machine stack.
1786 LD A,32 Signal 'error 32'.
1789 RET Exit.
Now the message can be printed.
178A PO_MSG1 POP HL HL points to the message to be printed
178B PO_MSG2 LD A,(HL) Fetch a character.
178C AND #7F
178E CALL #1799,PRT_A Print it.
1791 BIT 7,(HL) Bit 7 set signals 'End of message'.
1793 RET NZ
1794 INC HL
1795 JR #178B,PO_MSG2 Repeat for all characters.
THE 'PRINT A SPACE' SUBROUTINE
This subroutine prints a space to the current stream.
1797 PRT_SPACE LD A,32 Continue in the 'PRT_A' routine.
THE 'PRINT CHARACTER' SUBROUTINE
This subroutine prints the character held in the A register to the current stream.
1799 PRT_A PUSH AF
179A PUSH BC
179B PUSH DE
179C PUSH HL
179D PUSH IX
179F RST #10,CALBAS Print the character in the A register
17A0 DEFW #0010,PRINT_A_1 by calling the 'main' ROM routine.
17A2 POP IX
17A4 POP HL
17A5 POP DE
17A6 POP BC
17A7 POP AF
THE 'ROM' MESSAGES
Now follow some messages used by the +D system.
17A9 MESG_0 CALL #177E,PO_MSG
17AC DEFB #0D,#0D,#0D,#0D,#0D,#0D
17B2 DEFM " "SYSTEM" LOADING"
17CA DEFB #0D,#0D
17CC DEFM " PLEASE WAIT"
17E2 DEFB #0D,#0D
17E4 DEFM " (+D ROM Ver 1.A)"
17FC DEFB #0D,#8D
17FE MESG_1 CALL #177E,PO_MSG
1801 DEFM "OVERWRITE "
180B DEFB """+128
180C MESG_2 CALL #177E,PO_MSG
180F DEFM "Are you SURE ? (y/n"
1822 DEFB ")"+128
1823 MESG_3 CALL #177E,PO_MSG
1826 DEFM " (y/n)"
182C DEFB ")"+128