.def _InitBoot
    .ref _EntryAddr_H
    .ref _EntryAddr_L
 
    .sect ".InitBoot"
;
; _InitBoot
;
; 1) Initalizes the stack pointer
; 2) Sets the device for C28x operating mode
; 3) Calls the main boot functions
; 4) Calls an exit routine
;
_InitBoot:
; Initalize the stack pointer.
  MOV SP, #0 ; Initalize the stack pointer
; Initalize the device for running in C28x mode.
  C28OBJ ; Select C28x object mode
  C28ADDR ; Select C27x/C28x addressing
  C28MAP ; Set blocks M0/M1 for C28x mode
  CLRC PAGE0 ; Always use stack addressing mode
  MOVW DP,#0 ; Initialize DP to point to the low 64 K
  CLRC OVM
; Set PM shift of 0
  SPM 0
; Read the password locations – this will unlock the
; CSM only if the passwords are erased. Otherwise it
; will not have an effect.
  MOVL XAR1,#0x3F7FF8;
  MOVL XAR0,*XAR1++
  MOVL XAR0,*XAR1++
  MOVL XAR0,*XAR1++
  MOVL XAR0,*XAR1
; Cleanup and exit. At this point the EntryAddr
; is located in the ACC register
  BF _ExitBoot,UNC
;
; _ExitBoot
;
;
;This module cleans up after the boot loader
;
; 1) Make sure the stack is deallocated.
; SP = 0x400 after exiting the boot
; loader
; 2) Push 0 onto the stack so RPC will be
; 0 after using LRETR to jump to the
; entry point
; 2) Load RPC with the entry point
; 3) Clear all XARn registers
; 4) Clear ACC, P and XT registers
; 5) LRETR – this will also clear the RPC
; register since 0 was on the stack
;
_ExitBoot:
;
; Insure that the stack is deallocated
;
  MOV SP,#0
;
; Clear the bottom of the stack. This will endup
; in RPC when we are finished
;
  MOV *SP++,#0
  MOV *SP++,#0
  
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP  
;
; Load RPC with the entry point as determined
; by the boot mode. This address will be returned
; in the ACC register.
;
  MOV *SP++, #0x82CF
  MOV *SP++, #0x3F
  
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP 

  POP RPC
  
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP  
;
; Put registers back in their reset state.
;
; Clear all the XARn, ACC, XT, and P and DP
; registers
;
; NOTE: Leave the device in C28x operating mode
; (OBJMODE = 1, AMODE = 0)
;
  ZAPA
  MOVL XT,ACC
  MOVZ AR0,AL
  MOVZ AR1,AL
  MOVZ AR2,AL
  MOVZ AR3,AL
  MOVZ AR4,AL
  MOVZ AR5,AL
  MOVZ AR6,AL
  MOVZ AR7,AL
  MOVW DP, #0
;
; Restore ST0 and ST1. Note OBJMODE is
; the only bit not restored to its reset state.
; OBJMODE is left set for C28x object operating
; mode.
;
; ST0 = 0x0000 ST1 = 0x0A0B
; 15:10 OVC = 0 15:13 ARP = 0
; 9: 7 PM = 0 12 XF = 0
; 6 V = 0 11 M0M1MAP = 1
; 5 N = 0 10 reserved
; 4 Z = 0 9 OBJMODE = 1
; 3 C = 0 8 AMODE = 0
; 2 TC = 0 7 IDLESTAT = 0
; 1 OVM = 0 6 EALLOW = 0
; 0 SXM = 0 5 LOOP = 0
; 4 SPA = 0
; 3 VMAP = 1
; 2 PAGE0 = 0
; 1 DBGM = 1
; 0 INTM = 1
;
  MOV *SP++,#0
  MOV *SP++,#0x0A0B
  
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP 
  
  POP ST1
  POP ST0
  
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP
  NOP 
;
; Jump to the EntryAddr as defined by the
; boot mode selected and continue execution
;
  LRETR
;
    .end