Routines |
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Used by the routine at SAVE_ETC.
The verification process involves the loading of a block of data, a byte at a time, but the bytes are not stored - only checked. This routine is also used to load blocks of data that have been described with 'SCREEN$' or 'CODE'.
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VR_CONTRL | 07CB | PUSH HL | Save the 'pointer'. | |||||
07CC | LD L,(IX-$06) | Fetch the 'number of bytes' as described in the 'old' header. | ||||||
07CF | LD H,(IX-$05) | |||||||
07D2 | LD E,(IX+$0B) | Fetch also the number from the 'new' header. | ||||||
07D5 | LD D,(IX+$0C) | |||||||
07D8 | LD A,H | Jump forward if the 'length' is unspecified, e.g. 'LOAD name CODE' only. | ||||||
07D9 | OR L | |||||||
07DA | JR Z,VR_CONT_1 | |||||||
07DC | SBC HL,DE | Give report R if attempting to load a larger block than has been requested. | ||||||
07DE | JR C,REPORT_R | |||||||
07E0 | JR Z,VR_CONT_1 | Accept equal 'lengths'. | ||||||
07E2 | LD A,(IX+$00) | Also give report R if trying to verify blocks that are of unequal size. ('Old length' greater than 'new length'.) | ||||||
07E5 | CP $03 | |||||||
07E7 | JR NZ,REPORT_R | |||||||
The routine continues by considering the 'destination pointer'.
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VR_CONT_1 | 07E9 | POP HL | Fetch the 'pointer', i.e. the 'start'. | |||||
07EA | LD A,H | This 'pointer' will be used unless it is zero, in which case the 'start' found in the 'new' header will be used instead. | ||||||
07EB | OR L | |||||||
07EC | JR NZ,VR_CONT_2 | |||||||
07EE | LD L,(IX+$0D) | |||||||
07F1 | LD H,(IX+$0E) | |||||||
The verify/load flag is now considered and the actual load made.
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VR_CONT_2 | 07F4 | PUSH HL | Move the 'pointer' to the IX register pair. | |||||
07F5 | POP IX | |||||||
07F7 | LD A,($5C74) | Jump forward unless using the VERIFY command (T-ADDR-lo=+02), with the carry flag signalling 'LOAD'. | ||||||
07FA | CP $02 | |||||||
07FC | SCF | |||||||
07FD | JR NZ,VR_CONT_3 | |||||||
07FF | AND A | Signal 'VERIFY'. | ||||||
VR_CONT_3 | 0800 | LD A,$FF | Signal 'accept data block only' before loading the block. | |||||
This routine continues into LD_BLOCK.
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