| Example: |
.ORG 0x1000
CheckEELength:
ADIW R26, 0 ; If 'X' is zero, no parameter was passed on
BREQ ACheckEELength_Ret ; the command line, so just exit immediately
MOVW R24, R26 ; Point R25:R24 at buffer to be parsed
CALL AParseValue ; Extract one numeric value from the string
SBRS R21, BIT_PV_VALID ; If no value was parsed, just exit
RJMP ACheckEELength_Ret ; The ULONG value returned in R25:R24:R23:R22
MOVW R24, R22 ; The EEPROM pointer is the Low WORD of that
CALL AstrlenEEPROM ; The System Function being demonstrated
CALL ADumpRegisters ; Optional (for FLAGs); toggle on with '}'
CALL APrintWORD ; Print the WORD returned in R25:R24
LDI R25, ACSZ_BYTEs >> 8
LDI R24, ACSZ_BYTEs & 0xFF
CALL APrintFLASHASCIIz ; The string below, ending in CR, LF
CheckEELength_Ret:
RET
CSZ_BYTEs: .STRING " BYTEs in the EEPROM string\n" |
| Test it: |
m>DE+ 80 240
EEPROM contents:
0050: 6E 52 46 20 50 54 58 20-63 6F 6E 66 69 67 3A 00 nRF PTX config:.
0060: 7C 3F 3F 03 34 4E 06 31-44 65 6D 6F 32 44 65 6D |??.4N.1Demo2Dem
0070: 6F 33 34 35 36 31 44 65-6D 6F 3F 07 88 D0 07 00 o34561Demo?.....
0080: 6E 52 46 20 50 52 58 20-63 6F 6E 66 69 67 3A 00 nRF PRX config:.
0090: 7D 00 3F 03 34 4E 06 31-44 65 6D 6F 32 44 65 6D }.?.4N.1Demo2Dem
00A0: 6F 33 34 35 36 31 44 65-6D 6F 3F 07 88 D0 07 00 o34561Demo?.....
00B0: 3B 20 42 6F 6F 74 75 70-20 49 6E 69 74 3A 20 00 ; Bootup Init: .
00C0: 45 20 31 20 7E 3D 20 30-78 43 30 00 4E 2A 2A 00 E 1 ~= 0xC0.N**.
00D0: 4E 44 2B 00 45 53 20 34-37 39 3D 35 38 00 45 20 ND+.ES 479=58.E
00E0: 30 78 31 39 20 3D 20 30-78 32 35 00 45 20 30 78 0x19 = 0x25.E 0x
00F0: 32 30 20 3D 20 30 78 32-34 00 FF FF FF FF FF FF 20 = 0x24.......
0100: 45 00 57 01 30 78 35 30-30 20 3D 20 32 20 53 00 E.W.0x500 = 2 S.
0110: 54 53 32 20 30 78 35 30-30 00 45 53 57 20 30 78 TS2 0x500.ESW 0x
0120: 35 31 30 20 3D 20 31 20-53 00 00 64 73 20 30 20 510 = 1 S..ds 0
0130: 34 30 00 FF FF FF FF FF-FF FF FF FF FF FF FF FF 40..............
m>@ 0x1000 80
15 BYTEs in the EEPROM string
m>@ 0x1000 0xb0
15 BYTEs in the EEPROM string
m>@ 4096 0xc0
11 BYTEs in the EEPROM string
m>@ 4096 0xCC
3 BYTEs in the EEPROM string
m>@ 4096 0xCF
0 BYTEs in the EEPROM string
m>@ 4096 0xF0
9 BYTEs in the EEPROM string
m>@ 4096 0x130
2 BYTEs in the EEPROM string
m>@ 4096 0x138
0 BYTEs in the EEPROM string
m>
|
| Notes: |
Strings in EEPROM are considered terminated if they end in 0,
0xFE or 0xFF, since 0xFF is the unprogrammed value. |
| The string may begin with a NULL, 0xFE, or 0xFF, which
are all valid and will return zero length. |
| EEPROM addresses beyond the end of EEPROM (i.e., 0x400 or
greater) will readback as 0xFF.
|
| The ZERO flag has already been set or cleared, so no
comparison of R25:R24 need be done. |
Dropin:
(setup
code) |
; Setup for the strlenEEPROM() call:
; Passed: R25:R24 BYTE * bPtrEEPROM EEPROM address at which to begin counting
; Returns: R25:R24 WORD wCount, number of BYTEs before the terminator
; (Also:) ZERO FLAG set (TRUE) when length is zero (and R25:R24 = 0)
; clear (FALSE) when length is > 0 (and R25:R24 > 0)
; Alters: Only R24, R25, and the FLAGSs
; Notes: The terminator BYTE is 0, 0xFE, or 0xFF for EEPROM strings.
|
| Also see: |
The strcpy,
strlen,
and strlenPGM System Functions. |