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Elite on the BBC Micro

Inventory: TT210 (Disc version)

Name: TT210 [View in context] Type: Subroutine [Compare versions] Category: Inventory Summary: Show a list of current cargo in our hold, optionally to sell
Show a list of current cargo in our hold, either with the ability to sell (the Sell Cargo screen) or without (the Inventory screen), depending on the current view. Arguments: QQ11 The current view: * 4 = Sell Cargo * 8 = Inventory
.TT210 LDY #0 \ We're going to loop through all the available market \ items and check whether we have any in the hold (and, \ if we are in the Sell Cargo screen, whether we want \ to sell any items), so we set up a counter in Y to \ denote the current item and start it at 0 .TT211 STY QQ29 \ Store the current item number in QQ29 LDX QQ20,Y \ Fetch into X the amount of the current item that we BEQ TT212 \ have in our cargo hold, which is stored in QQ20+Y, \ and if there are no items of this type in the hold, \ jump down to TT212 to skip to the next item TYA \ Set Y = Y * 4, so this will act as an index into the ASL A \ market prices table at QQ23 for this item (as there ASL A \ are four bytes per item in the table) TAY LDA QQ23+1,Y \ Fetch byte #1 from the market prices table for the STA QQ19+1 \ current item and store it in QQ19+1, for use by the \ call to TT152 below TXA \ Store the amount of item in the hold (in X) on the PHA \ stack JSR TT69 \ Call TT69 to set Sentence Case and print a newline CLC \ Print recursive token 48 + QQ29, which will be in the LDA QQ29 \ range 48 ("FOOD") to 64 ("ALIEN ITEMS"), so this ADC #208 \ prints the current item's name JSR TT27 LDA #14 \ Move the text cursor to column 14, for the item's STA XC \ quantity PLA \ Restore the amount of item in the hold into X TAX CLC \ Print the 8-bit number in X to 3 digits, without a JSR pr2 \ decimal point JSR TT152 \ Print the unit ("t", "kg" or "g") for the market item \ whose byte #1 from the market prices table is in \ QQ19+1 (which we set up above) .TT212 LDY QQ29 \ Fetch the item number from QQ29 into Y, and increment INY \ Y to point to the next item CPY #17 \ If Y < 17 then loop back to TT211 to print the next BCC TT211 \ item in the hold RTS \ Otherwise return from the subroutine