Texas Instruments TI-83 Plus Manual page 55

Chapter 2: TI-83 Plus Specific Information
Routines:
LoadCIndPaged
LoadDEIndPaged
Recommended support routines that an application should include as part of
the application.
LoadCIndPaged_inc:
;
; fall thru and INC pointer past byte read
;
inc_BHL:
;
set
;
LoadDEIndPaged_inc:
– Cached
This method provides management of the ROM page and offset of data in the
archive while reading multiple bytes. These values are stored in predefined
system RAM locations. A 16 byte RAM cache is used to queue up consecutive
data from the archive. There are two routines used.
SetupPagedPtr
Inputs:
TI-83 Plus Developer Guide
HL register = offset on the ROM page to the byte(s) to copy
Copies a byte from the archive to C
C = byte from archive
B, HL = intact
Copies two bytes from the archive to DE
E = first byte read
D = second byte read
B, HL = location of the second byte, crossing a ROM
B_CALL
INC
BIT
RET
INC
RES
RET
B_CALL
JR
Sets the initial value of the system RAM used to track
the current read location and the current amount of data
in the cache. This must be called before any data is
actually read.
B register = ROM page of first byte to copy.
HL register = offset on the ROM page to the first byte(s) to copy.
page boundary is handled
LoadCIndPaged ; read byte from archive
HL ; increment offset in page
7,h ; cross page boundary?
Z ; no, B, HL = ROM page and
; offset
B ; increase ROM page number
7,H
6,H ; adjust offset to be in
; 4000h to 7FFFh
LoadDEIndPaged ; read 2 bytes from
; archive
inc_BHL ; move pointer to byte
; after 2 read
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Third Release May 28, 2002