Texas Instruments TMS320C3x User Manual page 729

Boot-Loader Source Code Listing
* Test for INT3 and, if set exclusively, proceed with serial boot load. Else,
* load AR3 with 1000h if INT0, 810000h if INT1 900000h if INT2. Also load ,
* appropriate boot strobe pointer
* reflect 32bit memory width. If (INT0 or INT1 or INT2) and INT3, turn on the
* handshake mode.
*================================================================================*
wait1 LDI
AND
CMPI
BEQ
LDI
ADDI
TSTB
LDINZ
BNZ
ADDI
TSTB
LDINZ
BNZ
ADDI
TSTB
LDINZ
BZ
exit3 TSTB
BZ
TSTB
LDI
exit2 LDI
LSH
OR
STI
LSH
*
*================================================== xx000010 –
* Process MEMORY WIDTH control word (32 bits long)
*================================================== xx001000 –
*
*
LDI
LDI
LDI
CALLU
loop2 TSTB
BNZ
LSH
LSH
LSH
BU
C-6
––> AR2 and force the boot strobe value to
IF,R0
0Fh,R0 ; clean
8,R0 ; test for INT3
serial ;*******; serial boot load mode
AR7,AR2
60h,AR2 ; 808060h (IOSTRB)
2,R0 ; test for
4080h,AR3 ; 810000h / 2**9
exit3 ;*******;
4,AR2 ; 808064h
1,R0 ; test for
8,AR3 ; 001000h / 2**9
exit3 ;*******;
4,AR2 ; 808068h
4,R0 ; test for
4800h,AR3 ; 900000h / 2**9
wait1 ;*******;
8,R0 ;*; test#1 – INT3 asserted
exit2 ;*; test#2 – INXF1 low (not used)
80h,IOF ;*; enable handshake mode if
6,IOF ;*; test#1 passed
0Fh,R2
16,R2 ; force boot data size to 32
*AR2,R2 ; force boot mem width to 32
R2,*AR2
9,AR3 ; boot mem start addr ––> AR3
read_mc,AR0 ; use memory to read cntrl words
;
1,R5 ; mem width = 1
32,AR6 ; mem reads = 32
read_m ; read memory once
1,R6
label4
–1,R6 ; look at next bit
–1,AR6 ; decr mem reads
1,R5 ; incr mem width
loop2 ;*******;
––> AR2
INT1
(STRB0) ––> AR2
INT0
(STRB1) ––> AR2
INT2
xx000001 – 1 bit
2 bit
xx000100 – 4 bit
8 bit
xx010000 – 16 bit
xx100000 – 32 bit
read_mc ––> AR0
(init)
(init)
(1st read)
––> R5