;========================================================================
;   FILE: ps2main.asm
;
;   This file contains the code that implements the ps2 interface to the
;   host. 
;
;REVISION_HISTORY:
;
;3/26/99 replaced command processor jump table "calls" with "jmps"
;
;2/10/99 Added XPAGEOFF,XPAGEON around command processor jump table
;
;8/25/98 Added a 250 usec delay after the reception of a RESET command but
;prior to the ACK of the command.  Some PC's did not like it without this delay.
;
;========================================================================


       XPAGEON

;RAM use for this module

ps2_flags:                      equ       ps2main_ram_base+0 ;flag byte
ps2_last_xmit:                  equ       ps2main_ram_base+1 ;last sent byte     
ps2_xmit_holding_reg:           equ       ps2main_ram_base+2 ;next byte to send
ps2_temp0:                      equ       ps2main_ram_base+3 ;temp register 1
ps2_temp1:                      equ       ps2main_ram_base+4 ;temp register 2
ps2_delay:                      equ       ps2main_ram_base+5 ;used for generating delays
ps2_ghost_flagsV:			  equ       ps2main_ram_base+6 ;used to detect PS2 ghost
c750ms_high_byteV:		  equ       ps2main_ram_base+7 ;used for generating delay
c750ms_low_byteV:			  equ       ps2main_ram_base+8 ;used for generating delay
PS2MAIN_RAM_SIZE:               equ       9

                     
;========================================================================
;   FUNCTION: ps2main
;
;   Main entry point for ps2. Sets up ports, initializes RAM,
;   calls initialization function for various modules, calls
;   the BAT function, then enters the main processing loop.
;
;
;
;========================================================================
soft_reset:
    di
    mov     a,0                             ;set psp stack to 0
    mov     psp,a                           ; 
    mov     a,0ffh                          ;set dsp stack to 0xff
    swap    a,dsp                           ;now we can call functions

ps2main:
    iowr    WATCHDOG_REG
    mov     A,NORMAL                         ;configure GPIO reg
    iowr    GPIO_CONFIG_REG
    mov     A,CLKH_DATAH
    iowr    USB_STATUS_CONTROL_REG          ;initialize control reg    

    ;clear variables local to this module

    CLEARRAM ps2main_ram_base,PS2MAIN_RAM_SIZE

    call    ksc_init_keyscan                    ;initialize the key scanner
    call    ps2key_init                         ;and ps2-specific key scanning routines        
    mov     A,PS2_ENABLED_INTERRUPTS            ;enable ps2 interrupts        
    iowr    GLOBAL_INTERRUPT_REG
    ei                                          ;enable interrupts                                                       
    call    ps2_BAT                             ;test the system
    mov     [ ps2_xmit_holding_reg],A           ;place result in holding register for transmission
    SETBIT  PS2_XMIT,ps2_flags                  ;set bit to indicate transmission necessary
    SETBIT   PS2_SCAN_KBD,ps2_flags              ;enable scanning
    mov     A,0
    mov     [dual_ifc_1ms],A
.loop:
    iowr    WATCHDOG_REG
    call    ps2_idle_loop                       ;do all stuff we need to whilst sitting around
    call    ps2_get_byte                        ;see if a byte has come in
    jnc     .l0
    call    ps2_do_command                      ;it has, kick off command processor
.l0:
    mov     A,[dual_ifc_1ms]                       ;else check for scanning interval  
    cmp     A,PS2_SCAN_INTERVAL                 ; 
    jc      .l1                                 ;not time to scan yet, loop

    mov     A,0                                 ;reset scanning interval
    mov     [dual_ifc_1ms],A       

    TSTBIT  PS2_SCAN_KBD,ps2_flags              ;if scanning enabled
    jz      .l1                                           
    call    ps2_scan_keys                       ;  scan the keyboard                       
.l1:
    TSTBIT  PS2_XMIT,ps2_flags                  ;  and if we're not sending something else
    jnz     .l2                                 
    call    ps2_getkey                          ;  see if the keyboard scan resulted in something
    jc      .l2                                 
    mov     [ ps2_xmit_holding_reg],A           ;  get it if so, place in holding register
    SETBIT  PS2_XMIT,ps2_flags                  ;  set flag indicating transmission necessary
.l2:
    jmp     .loop                               ;  and loop




;========================================================================
; FUNCTION: ps2_wait_byte
;
;
; waits for reception of a byte from the host. This is called to get
; extra bytes in a command from the host. While the byte is waited for,
; the idle loop is called to keep other tasks going.
;
; Returns:  A:  received byte from host
;           C:  1
;
;
;========================================================================

ps2_wait_byte:
    call    ps2_idle_loop                   ;do boring stuff
    call    ps2_get_byte                    ;see if host has sent us something
    jnc     ps2_wait_byte                   ;no, continue to wait
    ret                                     ;yes, return with carry set




;========================================================================
; FUNCTION: ps2_get_byte
;
;
; tries to get a byte from the host
;
; Returns:  A:  received byte from host
;           C:  1 if A is valid, 0 if no byte received
;
;========================================================================

ps2_get_byte:
   iord     USB_STATUS_CONTROL_REG                  ;if host inhibit condition,           
   and      A,PS2_CLOCK_BIT                      
   jz       .no                                     ;skip this whole operation
   iord     USB_STATUS_CONTROL_REG                  ;if host holding us off
   and      A,PS2_DATA_BIT                          ;skip too
   jnz      .no                                 

   iord     USB_STATUS_CONTROL_REG                  ;check for inhibit again
   and      A,PS2_CLOCK_BIT
   jz       .no                                 
   call     ps2_receive                             ;all ok, try for byte
   jc       .no1                                    ;if byte received
   SETC                                             ;set carry and exit
   ret

.no1:
   SETBIT       PS2_RESEND_REQUESTED,ps2_flags      ;if something went awry during reception,
                                                    ;flag a resend request
.no:
   CLEARC                                           ;indicate nothing gotten,gained

   ret


;========================================================================
; FUNCTION: ps2_idle_loop
;
; the idle loop does the things that must be done during times when nothing
; else is happening.
;
; Returns: nothing
;========================================================================

ps2_idle_loop:
   iord     USB_STATUS_CONTROL_REG              ;if host inhibit                  
   and      A,PS2_CLOCK_BIT                     ;don't bother with anything
   jz       .il2                                 
   TSTBIT   PS2_RESEND_REQUESTED,ps2_flags      ;if we need last transmission resent
   jz       .il0                             

   mov      A,PS2_RSND                          ;send a resend request
   call     ps2_send
   jc       .il2                             
   CLRBIT   PS2_RESEND_REQUESTED,ps2_flags      ;and clear the resend requirement
   jmp      .il2                             

.il0:
   TSTBIT   PS2_RESEND,ps2_flags                ;if host wants last byte resent
   jz       .il1                             

   mov      A,[ps2_last_xmit]                   ;get it
   call     ps2_send                            ;resent it
   jc       .il2                             
   CLRBIT   PS2_RESEND,ps2_flags                ;reset flag
   jmp  .il2                             

.il1:
   TSTBIT   PS2_XMIT,ps2_flags                  ;if we've got something interesting to send
   jz       .il2                             

   mov      A,[ps2_xmit_holding_reg]            ;get it
   call     ps2_send                            ;send it
   jc       .il2                             
   CLRBIT   PS2_XMIT,ps2_flags                  ;clear flag saying we've got something
   mov      A,[ps2_xmit_holding_reg]            ;save last transmission
   mov      [ ps2_last_xmit],A                   

.il2:
       ret                                     ;that is it



;========================================================================
; FUNCTION: ps2_do_command
;
; host command processor switch statement
;
; Returns: nothing
;========================================================================

ps2_do_command:

   sub      A,0EDh                              ;subtract off base of command                  
   jc       ps2_invalid_command                 ;whoops, bad command
   mov      X,A                                 ;else save zero-based command in X
                                                ;clear all resend requirementd
   CLRBIT  (PS2_RESEND_REQUESTED + PS2_RESEND),ps2_flags       
   mov      A,X                                 ;get back zero-based command
   rlc                                          ;prepare for case jump
                                             ;to proper routine
   jacc    .switch              

XPAGEOFF
.switch:
    jmp    ps2_set_status_indicators
    jmp    ps2_echo_enable
    jmp    ps2_invalid_command
    jmp    ps2_select_alternate_scan_code
    jmp    ps2_invalid_command
    jmp    ps2_read_id
    jmp    ps2_set_typematic_rate_delay
    jmp    ps2_enable
    jmp    ps2_default_disable
    jmp    ps2_set_default
    jmp    ps2_set_keys
    jmp    ps2_set_keys
    jmp    ps2_set_keys
    jmp    ps2_set_keys
    jmp    ps2_set_key_type
    jmp    ps2_set_key_type
    jmp    ps2_set_key_type
    jmp    ps2_resend
    jmp    ps2_reset
endswitch:
    jc      ps2_do_command                          ;if command failed,
    ret
XPAGEON

;========================================================================
; FUNCTION: ps2_invalid_command
;
; handles invalid commands
;
;
; Returns:
;   C = 0 for success
;========================================================================

ps2_invalid_command:
    SETBIT  PS2_RESEND_REQUESTED,ps2_flags          ;flag that we need a resend
    CLEARC                                          ;clear C indicating we're done
    jmp     endswitch                               ;and return



;========================================================================
; FUNCTION: ps2_set_status_indicators
;
; sets indicator leds
;
; Returns:
;
;   C: 0 if command was sucessful
;   C: 1 if command failed 
;
;========================================================================

ps2_set_status_indicators:
    call    ps2_ack_byte                ;ack this command
    call    ps2_wait_byte               ;wait for 2nd byte
    cmp           A,8                   ;if 2nd byte invalid                             
    jc           .ed0                                
    SETC                                ;indicate it
    jmp     endswitch                   ;and return

.ed0:                                   ;else
    and     A,7                         ;mask off all but 3 ls bits
    index   ps2_led_tbl                 ;use translation table 
    push    A                           ;save it
    call    ksc_writeLED              ;write the leds
    pop     A                           ;get it back
    and     A,NUM_LOCK_LED              ;save state of numlock
    mov     [ps2key_numlock],A          ;locally
    call    ps2_ack_byte                ;ack this byte too
    CLEARC                              ;indicate we are done
    jmp     endswitch


;table to translate ps2-command enumeration of leds into our own bits
XPAGEOFF
ps2_led_tbl:
    db  0
    db  SCROLL_LOCK_LED
       db       NUM_LOCK_LED
    db  SCROLL_LOCK_LED + NUM_LOCK_LED
    db  CAPS_LOCK_LED
    db  CAPS_LOCK_LED + SCROLL_LOCK_LED
    db  CAPS_LOCK_LED + NUM_LOCK_LED
    db  CAPS_LOCK_LED + NUM_LOCK_LED + SCROLL_LOCK_LED       
XPAGEON





;========================================================================
; 
; FUNCTION: ps2_echo_enable -- burps back an echo byte
;
; Returns:
;
;   C: 0 command can't fail
;========================================================================

ps2_echo_enable:
    mov     A,PS2_ECHO                      ;send echo response
    call    ps2_put_byte                        ;and respond
    CLEARC
    jmp     endswitch

;========================================================================
;   FUNCTION: ps2_select_alternate_scan_code
;
; Returns:
;