Texas Instruments TI-83-Plus - Page 65

Chapter 2: TI-83 Plus Specific Information 55
TI-83 Plus Developer Guide Third Release May 28, 2002
Example: A routine that traverses both sections of the Symbol Table.
Traverse_symTable:
LD HL,symTable ; HL = pointer to first symbol entry
LD D,0
LD BC,(pTemp) ; BC = pointer to byte after the end
; of the Symbol Table
loop:
OR A
SBC HL,BC ; current - end, if CA then done with
; search
RET C ; return if no more syms to check
RET Z ; return if no more to check
;
ADD HL,BC ; restore current search pointer
LD A,(HL) ; get symbol entry type
AND 1Fh ; mask off variable type
;
LD E,6 ; DE = offset to NL or first byte of
; name
SBC HL,DE ; (HL) = NL or first byte of name
;
LD E,3 ; DE = offset to next entry if not a
; program/list/group/AppVar
CP AppVarObj ; current entry an AppVar
JR Z,movetonext ; yes, get NL to find next entry
;
CP ProgObj ; current entry a program
JR Z,movetonext ; yes, get NL to find next entry
;
CP ProtProgObj ; current entry a program
JR Z,movetonext ; yes, get NL to find next entry
;
CP TempProjObj ; current entry a program
JR Z,movetonext ; yes, get NL to find next entry
;
CP groupprogobj ; current entry a group var
JR Z,movetonext ; yes, get NL to find next entry
;
DEC HL ; (HL) = tVarLst if a list
LD A,(HL)
INC HL ; fix
CP tVarLst ; current entry a list
JR NZ,movetonext1 ; no
Movetonext:
LD E,(HL) ; DE = length of name
INC E ; DE = length of name + 1
;
; move HL to next symbol table entry sign digit
;
Movetonext1:
OR A
SBC HL,DE ; HL = next symbol table entry address
JR loop