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Elite on the BBC Micro

Equipment: EQSHP [Cassette version]

Name: EQSHP [Show more] Type: Subroutine Category: Equipment Summary: Show the Equip Ship screen (red key f3)
Context: See this subroutine in context in the source code Variations: See code variations for this subroutine in the different versions References: This subroutine is called as follows: * TT102 calls EQSHP * eq calls entry point err

Other entry points: err Beep, pause and go to the docking bay (i.e. show the Status Mode screen) pres Given an item number A with the item name in recursive token Y, show an error to say that the item is already present, refund the cost of the item, and then beep and exit to the docking bay (i.e. show the Status Mode screen)
.bay JMP BAY \ Go to the docking bay (i.e. show the Status Mode \ screen) .EQSHP JSR DIALS \ Call DIALS to update the dashboard LDA #32 \ Clear the top part of the screen, draw a white border, JSR TT66 \ and set the current view type in QQ11 to 32 (Equip \ Ship screen) LDA #12 \ Move the text cursor to column 12 STA XC LDA #207 \ Print recursive token 47 ("EQUIP") followed by a space JSR spc LDA #185 \ Print recursive token 25 ("SHIP") and draw a JSR NLIN3 \ horizontal line at pixel row 19 to box in the title LDA #%10000000 \ Set bit 7 of QQ17 to switch to Sentence Case, with the STA QQ17 \ next letter in capitals INC YC \ Move the text cursor down one line LDA tek \ Fetch the tech level of the current system from tek CLC \ and add 3 (the tech level is stored as 0-14, so A is ADC #3 \ now set to between 3 and 17) CMP #12 \ If A >= 12 then set A = 12, so A is now set to between BCC P%+4 \ 3 and 12 LDA #12 STA Q \ Set QQ25 = A (so QQ25 is in the range 3-12 and STA QQ25 \ represents number of the most advanced item available INC Q \ in this system, which we can pass to gnum below when \ asking which item we want to buy) \ \ Set Q = A + 1 (so Q is in the range 4-13 and contains \ QQ25 + 1, i.e. the highest item number on sale + 1) LDA #70 \ Set A = 70 - QQ14, where QQ14 contains the current SEC \ fuel in light years * 10, so this leaves the amount SBC QQ14 \ of fuel we need to fill 'er up (in light years * 10) ASL A \ The price of fuel is always 2 Cr per light year, so we STA PRXS \ double A and store it in PRXS, as the first price in \ the price list (which is reserved for fuel), and \ because the table contains prices as price * 10, it's \ in the right format (so tank containing 7.0 light \ years of fuel would be 14.0 Cr, or a PRXS value of \ 140) LDX #1 \ We are now going to work our way through the equipment \ price list at PRXS, printing out the equipment that is \ available at this station, so set a counter in X, \ starting at 1, to hold the number of the current item \ plus 1 (so the item number in X loops through 1-13) .EQL1 STX XX13 \ Store the current item number + 1 in XX13 JSR TT67 \ Print a newline LDX XX13 \ Print the current item number + 1 to 3 digits, left- CLC \ padding with spaces, and with no decimal point, so the JSR pr2 \ items are numbered from 1 JSR TT162 \ Print a space LDA XX13 \ Print recursive token 104 + XX13, which will be in the CLC \ range 105 ("FUEL") to 116 ("GALACTIC HYPERSPACE ") ADC #104 \ so this prints the current item's name JSR TT27 LDA XX13 \ Call prx-3 to set (Y X) to the price of the item with JSR prx-3 \ number XX13 - 1 (as XX13 contains the item number + 1) SEC \ Set the C flag so we will print a decimal point when \ we print the price LDA #25 \ Move the text cursor to column 25 STA XC LDA #6 \ Print the number in (Y X) to 6 digits, left-padding JSR TT11 \ with spaces and including a decimal point, which will \ be the correct price for this item as (Y X) contains \ the price * 10, so the trailing zero will go after the \ decimal point (i.e. 5250 will be printed as 525.0) LDX XX13 \ Increment the current item number in XX13 INX CPX Q \ If X < Q, loop back up to print the next item on the BCC EQL1 \ list of equipment available at this station JSR CLYNS \ Clear the bottom three text rows of the upper screen, \ and move the text cursor to column 1 on row 21, i.e. \ the start of the top row of the three bottom rows LDA #127 \ Print recursive token 127 ("ITEM") followed by a JSR prq \ question mark JSR gnum \ Call gnum to get a number from the keyboard, which \ will be the number of the item we want to purchase, \ returning the number entered in A and R, and setting \ the C flag if the number is bigger than the highest \ item number in QQ25 BEQ bay \ If no number was entered, jump up to bay to go to the \ docking bay (i.e. show the Status Mode screen) BCS bay \ If the number entered was too big, jump up to bay to \ go to the docking bay (i.e. show the Status Mode \ screen) SBC #0 \ Set A to the number entered - 1 (because the C flag is \ clear), which will be the actual item number we want \ to buy LDX #2 \ Move the text cursor to column 2 STX XC INC YC \ Move the text cursor down one line PHA \ While preserving the value in A, call eq to subtract JSR eq \ the price of the item we want to buy (which is in A) PLA \ from our cash pot, but only if we have enough cash in \ the pot. If we don't have enough cash, exit to the \ docking bay (i.e. show the Status Mode screen) BNE et0 \ If A is not 0 (i.e. the item we've just bought is not \ fuel), skip to et0 STA MCNT \ We just bought fuel, so we zero the main loop counter LDX #70 \ Set the current fuel level * 10 in QQ14 to 70, or 7.0 STX QQ14 \ light years (a full tank) .et0 CMP #1 \ If A is not 1 (i.e. the item we've just bought is not BNE et1 \ a missile), skip to et1 LDX NOMSL \ Fetch the current number of missiles from NOMSL into X INX \ Increment X to the new number of missiles LDY #117 \ Set Y to recursive token 117 ("ALL") CPX #5 \ If buying this missile would give us 5 missiles, this BCS pres \ is more than the maximum of 4 missiles that we can \ fit, so jump to pres to show the error "All Present", \ beep and exit to the docking bay (i.e. show the Status \ Mode screen) STX NOMSL \ Otherwise update the number of missiles in NOMSL JSR msblob \ Reset the dashboard's missile indicators so none of \ them are targeted .et1 LDY #107 \ Set Y to recursive token 107 ("LARGE CARGO{sentence \ case} BAY") CMP #2 \ If A is not 2 (i.e. the item we've just bought is not BNE et2 \ a large cargo bay), skip to et2 LDX #37 \ If our current cargo capacity in CRGO is 37, then we CPX CRGO \ already have a large cargo bay fitted, so jump to pres BEQ pres \ to show the error "Large Cargo Bay Present", beep and \ exit to the docking bay (i.e. show the Status Mode \ screen) STX CRGO \ Otherwise we just scored ourselves a large cargo bay, \ so update our current cargo capacity in CRGO to 37 .et2 CMP #3 \ If A is not 3 (i.e. the item we've just bought is not BNE et3 \ an E.C.M. system), skip to et3 INY \ Increment Y to recursive token 108 ("E.C.M.SYSTEM") LDX ECM \ If we already have an E.C.M. fitted (i.e. ECM is BNE pres \ non-zero), jump to pres to show the error "E.C.M. \ System Present", beep and exit to the docking bay \ (i.e. show the Status Mode screen) DEC ECM \ Otherwise we just took delivery of a brand new E.C.M. \ system, so set ECM to &FF (as ECM was 0 before the DEC \ instruction) .et3 CMP #4 \ If A is not 4 (i.e. the item we've just bought is not BNE et4 \ an extra pulse laser), skip to et4 JSR qv \ Print a menu listing the four views, with a "View ?" \ prompt, and ask for a view number, which is returned \ in X (which now contains 0-3) LDA #4 \ This instruction doesn't appear to do anything, as we \ either don't need it (if we already have this laser) \ or we set A to 4 below (if we buy it) LDY LASER,X \ If there is no laser mounted in the chosen view (i.e. BEQ ed4 \ LASER+X, which contains the laser power for view X, is \ zero), jump to ed4 to buy a pulse laser .ed7 LDY #187 \ Otherwise we already have a laser mounted in this BNE pres \ view, so jump to pres with Y set to token 27 \ (" LASER") to show the error "Laser Present", beep \ and exit to the docking bay (i.e. show the Status \ Mode screen) .ed4 LDA #POW \ We just bought a pulse laser for view X, so we need STA LASER,X \ to fit it by storing the laser power for a pulse laser \ (given in POW) in LASER+X LDA #4 \ Set A to 4 as we just overwrote the original value, \ and we still need it set correctly so we can continue \ through the conditional statements for all the other \ equipment .et4 CMP #5 \ If A is not 5 (i.e. the item we've just bought is not BNE et5 \ an extra beam laser), skip to et5 JSR qv \ Print a menu listing the four views, with a "View ?" \ prompt, and ask for a view number, which is returned \ in X (which now contains 0-3) STX T1 \ Store the view in T1 so we can retrieve it below LDA #5 \ Set A to 5 as the call to qv will have overwritten \ the original value, and we still need it set \ correctly so we can continue through the conditional \ statements for all the other equipment LDY LASER,X \ If there is no laser mounted in the chosen view (i.e. BEQ ed5 \ LASER+X, which contains the laser power for view X, \ is zero), jump to ed5 to buy a beam laser \BPL P%+4 \ This instruction is commented out in the original \ source, though it would have no effect (it would \ simply skip the BMI if A is positive, which is what \ BMI does anyway) BMI ed7 \ If there is a beam laser already mounted in the chosen \ view (i.e. LASER+X has bit 7 set, which indicates a \ beam laser rather than a pulse laser), skip back to \ ed7 to print a "Laser Present" error, beep and exit \ to the docking bay (i.e. show the Status Mode screen) LDA #4 \ If we get here then we already have a pulse laser in JSR prx \ the selected view, so we call prx to set (Y X) to the \ price of equipment item number 4 (extra pulse laser) \ so we can give a refund of the pulse laser JSR MCASH \ Add (Y X) cash to the cash pot in CASH, so we refund \ the price of the pulse laser we are exchanging for a \ new beam laser .ed5 LDA #POW+128 \ We just bought a beam laser for view X, so we need LDX T1 \ to fit it by storing the laser power for a beam laser STA LASER,X \ (given in POW+128) in LASER+X, using the view number \ we stored in T1 earlier, as the call to prx will have \ overwritten the original value in X .et5 LDY #111 \ Set Y to recursive token 107 ("FUEL SCOOPS") CMP #6 \ If A is not 6 (i.e. the item we've just bought is not BNE et6 \ a fuel scoop), skip to et6 LDX BST \ If we already have fuel scoops fitted (i.e. BST is BEQ ed9 \ zero), jump to ed9, otherwise fall through into pres \ to show the error "Fuel Scoops Present", beep and \ exit to the docking bay (i.e. show the Status Mode \ screen) .pres \ If we get here we need to show an error to say that \ the item whose name is in recursive token Y is already \ present, and then process a refund for the cost of \ item number A STY K \ Store the item's name in K JSR prx \ Call prx to set (Y X) to the price of equipment item \ number A JSR MCASH \ Add (Y X) cash to the cash pot in CASH, as the station \ already took the money for this item in the JSR eq \ instruction above, but we can't fit the item, so need \ our money back LDA K \ Print the recursive token in K (the item's name) JSR spc \ followed by a space LDA #31 \ Print recursive token 145 ("PRESENT") JSR TT27 .err JSR dn2 \ Call dn2 to make a short, high beep and delay for 1 \ second JMP BAY \ Jump to BAY to go to the docking bay (i.e. show the \ Status Mode screen) .ed9 DEC BST \ We just bought a shiny new fuel scoop, so set BST to \ &FF (as BST was 0 before the jump to ed9 above) .et6 INY \ Increment Y to recursive token 112 ("E.C.M.SYSTEM") CMP #7 \ If A is not 7 (i.e. the item we've just bought is not BNE et7 \ an escape pod), skip to et7 LDX ESCP \ If we already have an escape pod fitted (i.e. ESCP is BNE pres \ non-zero), jump to pres to show the error "Escape Pod \ Present", beep and exit to the docking bay (i.e. show \ the Status Mode screen) DEC ESCP \ Otherwise we just bought an escape pod, so set ESCP \ to &FF (as ESCP was 0 before the DEC instruction) .et7 INY \ Increment Y to recursive token 113 ("ENERGY BOMB") CMP #8 \ If A is not 8 (i.e. the item we've just bought is not BNE et8 \ an energy bomb), skip to et8 LDX BOMB \ If we already have an energy bomb fitted (i.e. BOMB BNE pres \ is non-zero), jump to pres to show the error "Energy \ Bomb Present", beep and exit to the docking bay (i.e. \ show the Status Mode screen) LDX #&7F \ Otherwise we just bought an energy bomb, so set BOMB STX BOMB \ to &7F .et8 INY \ Increment Y to recursive token 114 ("ENERGY UNIT") CMP #9 \ If A is not 9 (i.e. the item we've just bought is not BNE etA \ an energy unit), skip to etA LDX ENGY \ If we already have an energy unit fitted (i.e. ENGY is BNE pres \ non-zero), jump to pres to show the error "Energy Unit \ Present", beep and exit to the docking bay (i.e. show \ the Status Mode screen) INC ENGY \ Otherwise we just picked up an energy unit, so set \ ENGY to 1 (as ENGY was 0 before the INC instruction) .etA INY \ Increment Y to recursive token 115 ("DOCKING \ COMPUTERS") CMP #10 \ If A is not 10 (i.e. the item we've just bought is not BNE etB \ a docking computer), skip to etB LDX DKCMP \ If we already have a docking computer fitted (i.e. BNE pres \ DKCMP is non-zero), jump to pres to show the error \ "Docking Computer Present", beep and exit to the \ docking bay (i.e. show the Status Mode screen) DEC DKCMP \ Otherwise we just got hold of a docking computer, so \ set DKCMP to &FF (as DKCMP was 0 before the DEC \ instruction) .etB INY \ Increment Y to recursive token 116 ("GALACTIC \ HYPERSPACE ") CMP #11 \ If A is not 11 (i.e. the item we've just bought is not BNE et9 \ a galactic hyperdrive), skip to et9 LDX GHYP \ If we already have a galactic hyperdrive fitted (i.e. BNE pres \ GHYP is non-zero), jump to pres to show the error \ "Galactic Hyperspace Present", beep and exit to the \ docking bay (i.e. show the Status Mode screen) DEC GHYP \ Otherwise we just splashed out on a galactic \ hyperdrive, so set GHYP to &FF (as GHYP was 0 before \ the DEC instruction) .et9 JSR dn \ We are done buying equipment, so print the amount of \ cash left in the cash pot, then make a short, high \ beep to confirm the purchase, and delay for 1 second JMP EQSHP \ Jump back up to EQSHP to show the Equip Ship screen \ again and see if we can't track down another bargain