Routines
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6074: Run Script Table
Used by the routine at ObeyCommand.
Walks a bytecode table. A line whose verb and noun match is executed; a failed condition or a bit-6 action stops the line. 7F ends the table.
The ordinary command scripts live at CommandScripts and are marked by a clear script-set flag.
RunScripts 6074 LD HL,$9A54 Select the ordinary scripts. The high-priority entry joins here.
6077 XOR A
6078 LD ($5B96),A
This entry point is used by the routine at RunPriorityScripts.
RunScripts_Line 607B PUSH HL Keep the line pointer in DE while HL walks it.
607C POP DE
607D XOR A No line has matched yet, and no condition has failed.
607E LD ($5B79),A
6081 LD ($5ECA),A
6084 CALL MatchCommand Call MatchCommand to test the verb and noun.
6087 JR RunScripts_Next The next byte is a condition or an action.
RunScripts_Failed 6089 XOR A A failed line is abandoned and the next one is tried.
608A LD ($5ECA),A
608D CALL SkipLine
RunScripts_Next 6090 LD A,H Return at the 7F end marker.
6091 OR L
6092 RET Z
6093 BIT 7,(HL) Bit 7 on the current byte starts the actions.
6095 JR NZ,RunScripts_Matched
A condition byte, shifted, picks a routine from 67CB. The object byte in front of it is looked up in ObjectLocations.
RunScripts_Condition 6097 LD A,(HL) Shift the condition number so it indexes a word.
6098 SLA A
609A LD IX,$67CB Index the condition table at 67CB.
609E LD C,A
609F LD B,$00
60A1 ADD IX,BC
60A3 LD A,(IX+$00) Plant that routine over the call at 60C1.
60A6 LD ($60C2),A
60A9 LD A,(IX+$01)
60AC LD ($60C3),A
60AF PUSH HL The next bytecode byte is the object number.
60B0 INC HL
60B1 LD A,(HL)
60B2 LD C,A
60B3 LD IX,$5DCA Point at that object's location in ObjectLocations.
60B7 ADD IX,BC
60B9 LD B,A The location itself is what the condition compares.
60BA LD A,(IX+$00)
60BD LD C,A
60BE INC HL The byte after the object is the condition's parameter.
60BF LD A,(HL)
60C0 PUSH DE
60C1 CALL $0006 The condition routine returns normally when it passes, or sets ConditionFailed when it fails.
60C4 POP DE
60C5 POP HL
60C6 CALL SkipCondition
60C9 LD A,($5ECA) A failure skips the rest of this line.
60CC OR A
60CD JR NZ,RunScripts_Failed
60CF BIT 7,(HL) Otherwise keep testing while bit 7 is clear.
60D1 JR Z,RunScripts_Condition
The line matched. Remember that, and perform each action until one asks to stop.
RunScripts_Matched 60D3 LD A,$01 Remember that a line matched.
60D5 LD ($5B79),A
RunScripts_NextAction 60D8 LD A,($5B86) The word slot is clear, so nothing to forget.
60DB OR A
60DC JR Z,RunScripts_Action
60DE XOR A The first matched line of a command clears WordSlot.
60DF LD ($5B86),A
RunScripts_Action 60E2 BIT 6,(HL) Bit 6 asks the runner to stop after this action.
60E4 JR Z,RunScripts_Do
60E6 LD A,$01
60E8 LD ($5ECA),A
RunScripts_Do 60EB LD A,(HL) Keep the action number in the low six bits and double it.
60EC AND $3F
60EE SLA A
60F0 LD IX,$6AD5 Index from the word inside 6AD4. Action 0 is the beeper operand; the routines start at ActionTable.
60F4 LD C,A
60F5 LD B,$00
60F7 ADD IX,BC
60F9 LD A,(IX+$00) Plant that routine over the call at 6117.
60FC LD ($6118),A
60FF LD A,(IX+$01)
6102 LD ($6119),A
6105 PUSH HL The next bytecode byte is the object number.
6106 INC HL
6107 LD A,(HL)
6108 LD IX,$5DCA Point at that object's location in ObjectLocations.
610C LD C,A
610D ADD IX,BC
610F LD B,A The location itself is passed to the action.
6110 LD A,(IX+$00)
6113 LD C,A
6114 INC HL The byte after the object is the action's parameter.
6115 LD A,(HL)
6116 PUSH DE
6117 CALL $0006 Call the patched action.
611A POP DE Restore the line pointer and the table pointer.
611B POP HL
611C CALL SkipAction Call SkipAction to step past the action.
611F LD A,($5ECA) Stop the table when the action raised ConditionFailed.
6122 OR A
6123 RET NZ
6124 BIT 7,(HL) Bit 7 continues this line's next action.
6126 JR NZ,RunScripts_NextAction
6128 JP RunScripts_Failed Jump to RunScripts_Failed to start the next line.
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