80-Bus News

  

January–February 1984, Volume 3, Issue 1











Page 29 of 55











Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    65

F382 0101F1     LEN:    LD      BC,PASSA        ; To return integer A
F385 C5                 PUSH    BC              ; Save address
F386 CD50F3     GETLEN: CALL    GETSTR          ; Get string and its length
F389 AF                 XOR     A
F38A 57                 LD      D,A             ; Clear D
F38B 32AD10             LD      (TYPE),A        ; Set type to numeric
F38E 7E                 LD      A,(HL)          ; Get length of string
F38F B7                 OR      A               ; Set status flags
F390 C9                 RET

F391 0101F1     ASC:    LD      BC,PASSA        ; To return integer A
F394 C5                 PUSH    BC              ; Save address
F395 CD86F3     GTFLNM: CALL    GETLEN          ; Get length of string
F398 CAA0E9             JP      Z,FCERR         ; Null string - Error
F39B 23                 INC     HL
F39C 23                 INC     HL
F39D 5E                 LD      E,(HL)          ; Get LSB of address
F39E 23                 INC     HL
F39F 56                 LD      D,(HL)          ; Get MSB of address
F3A0 1A                 LD      A,(DE)          ; Get first byte of string
F3A1 C9                 RET

F3A2 3E01       CHR:    LD      A,1             ; One character string
F3A4 CDBFF1             CALL    MKTMST          ; Make a temporary string
F3A7 CD87F4             CALL    MAKINT          ; Make it integer A
F3AA 2AC110             LD      HL,(TMPSTR+2)   ; Get address of string
F3AD 73                 LD      (HL),E          ; Save character
F3AE C1         TOPOOL: POP     BC              ; Clean up stack
F3AF C3F0F1             JP      TSTOPL          ; Temporary string to pool
Dis-assembly of NASCOM ROM BASIC Ver 4.7                PAGE    66

F3B2 CD37F4     LEFT:   CALL    LFRGNM          ; Get number and ending ")"
F3B5 AF                 XOR     A               ; Start at first byte in string
F3B6 E3         RIGHT1: EX      (SP),HL         ; Save code string,Get string
F3B7 4F                 LD      C,A             ; Starting position in string
F3B8 E5         MID1:   PUSH    HL              ; Save string block address
F3B9 7E                 LD      A,(HL)          ; Get length of string
F3BA B8                 CP      B               ; Compare with number given
F3BB DAC0F3             JP      C,ALLFOL        ; All following bytes required
F3BE 78                 LD      A,B             ; Get new length
F3BF 11                 DEFB    (LD DE,nn)      ; Skip "LD C,0"
F3C0 0E00       ALLFOL: LD      C,0             ; First byte of string
F3C2 C5                 PUSH    BC              ; Save position in string
F3C3 CD29F2             CALL    TESTR           ; See if enough string space
F3C6 C1                 POP     BC              ; Get position in string
F3C7 E1                 POP     HL              ; Restore string block address
F3C8 E5                 PUSH    HL              ; And re-save it
F3C9 23                 INC     HL
F3CA 23                 INC     HL
F3CB 46                 LD      B,(HL)          ; Get LSB of address
F3CC 23                 INC     HL
F3CD 66                 LD      H,(HL)          ; Get MSB of address
F3CE 68                 LD      L,B             ; HL = address of string
F3CF 0600               LD      B,0             ; BC = starting address
F3D1 09                 ADD     HL,BC           ; Point to that byte
F3D2 44                 LD      B,H             ; BC = source string
F3D3 4D                 LD      C,L
F3D4 CDC2F1             CALL    CRTMST          ; Create a string entry
F3D7 6F                 LD      L,A             ; Length of new string
F3D8 CD46F3             CALL    TOSTRA          ; Move string to string area
F3DB D1                 POP     DE              ; Clear stack
F3DC CD57F3             CALL    GSTRDE          ; Move to string pool if needed
F3DF C3F0F1             JP      TSTOPL          ; Temporary string to pool

F3E2 CD37F4     RIGHT:  CALL    LFRGNM          ; Get number and ending ")"
F3E5 D1                 POP     DE              ; Get string length
F3E6 D5                 PUSH    DE              ; And re-save
F3E7 1A                 LD      A,(DE)          ; Get length
F3E8 90                 SUB     B               ; Move back N bytes
F3E9 C3B6F3             JP      RIGHT1          ; Go and get sub-string

This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 29 of 55