Motorola DSP56012 ユーザーズマニュアル

; “shild” is the routine that loads from the Serial Host Interface.

; MC:MB:MA = 101—bootstrap  from SHI (SPI)

; MC:MB:MA = 111—bootstrap  from SHI (IIC)

; If MC:MB:MA = 1X1, the internal Program RAM is loaded with 256 words 

; received through the Serial Host Interface (SHI).

; The SHI operates in the Slave mode

; with the 10-word FIFO enabled, and with the HREQ pin enabled for

; receive operation. The word size for transfer is 24 bits. The SHI

; operates in the SPI or in the IIC mode, according to the bootstrap mode.

 

shild          jclr    #mb,omr,shi_loop ; If MC:MB:MA = 101, select SPI mode

 

               bset    #hi2c,r1         ; otherwise select I2C mode.

shi_loop       movep

r1,x:hcsr        ; enable SHI

               do      #256,_loop2

               jclr    #hrne,x:hcsr,*   ; wait for HRX not empty

               movep   x:hrx,p:(r0)+    ; store in Program RAM

_loop2

; Exit bootstrap ROM

exit 

               clr a   a0,r0            ; r0 points to destination address 

               andi    #$ec,omr         ; set operating mode to 0

                                        ; (and trigger an exit from

                                        ; bootstrap mode).

               movep   a1,x:bcr         ; Delay needed for Op. Mode change

                                        ; used to clear BCR register.

               jmp     (r0)             ; Then go to destination address.

               

; This code fills the unused bootstrap ROM locations with their address

               dup $020-*

               dc *

               endm