Texas Instruments TMS320F20x/F24x DSP manual Preliminary, Assembly Source for Algorithms, A-12

Assembly Source for Algorithms

PRELIMINARY

CLRC	OVM	;Disable overflow mode.
LACL	SEG_ST	;Get segment start address.
AND	#04000h	;Get array start address.
SACL	FL_ST	;Save array start address.
OR	#03FFFh	;Get array end address.
SACL	FL_END	;Save array end address.
SPLK	#0,ERROR	;Reset error flag
LAR	AR1,#0	;Set erase count to 0.
SPLK	#STOP, BASE_0 ;Stop command.
CALL	SET_MODE	;Disable any flash cmds.

XOR_ERASE

** Compute checksum for flash, using address complementing.**

LACC	SEG_END
SUB	SEG_ST
SAC	BASE_4	;Segment length±1.
LAR	AR2,BASE_4	;load n±1 to loop n times.
ADD	#1
SACL	BASE_4	;Segment length.
SPLK	#VER1,BASE_0	;VER1 command.
CALL	SET_MODE	;Set VER1 mode.
MAR	*,AR2
BLDD	#SEG_ST,BASE_1	;Segment start address.
SPLK	#0,BASE_3	;Clear checksum.
RD1_LOOP		;For I = SEG_ST to SEG_END.
LACC	BASE_1	;ACC => CURRENT ADDR.
XOR	FL_END	;XOR addr with flash end addr.
TBLR	BASE_2	;Dummy Read.
LACC	BASE_1	;Get actual addr again.
TBLR	BASE_2	;True Read.
ADD	#1	;Increment flash addr.
SACL	BASE_1	;Store for next read.
LACC	BASE_3	;Get old check sum.
ADD	BASE_2	;ACC=>ACC+FL_DATA.
SACL	BASE_3	;Save new check sum.
BANZ	RD1_LOOP,*±
ADD	BASE_4	;Should make ACC = 0 for
		;erased array.
BCND	XOR_ERFIN,EQ	;If BASE_3 = 0, finished.
***** If not erased, apply an		erase pulse.
CALL	ERASE_A	;Else, pulse it again.
MAR	*,AR1	;ARP±>AR1 (Erase pulse count)
MAR	*+	;Increment Erase count.
LAR	AR0,#MAX_ER
CMPR2		;If AR1>MAX_ER then
BCND	EXIT,TC	;fail, don't continue erasing.
B	XOR_ERASE	;Else, check again.

*****If here, then erase passed; now check for depletion.

XOR_ERFIN

SPLK	#STOP, BASE_0	;Stop command.
CALL	SET_MODE	;Disable any flash cmds.
CALL	INV_ERASE	;Check for depletion.
DONE RET		;Return to calling code.

A-12 PRELIMINARY