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Miscalleneous routines II 

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)
with RBCC.

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.
168D            RET

This subroutine is used whenever the border colour was changed during an I/O operation,
and needs to be restored to its original state.

168F            LD   A,(23624)           Fetch lower screen attribute (BORDCR).
1692            AND  #38                 Only the border bits.
1694            RRCA                     Move the bits to 0-2.
1695            RRCA
1696            RRCA
1697            OUT  (254),A             Restore colour.
1699            POP  AF
169A            RET

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.

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

This table contains the directory description messages as printed with an 'extended
CAT'. Each message is preceeded by is description value.

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

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

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'.

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'.
1788            SCF
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.

This subroutine prints a space to the current stream.

1797 PRT_SPACE  LD   A,32                Continue in the 'PRT_A' routine.

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
17A8            RET

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

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