.send_error: 
	mov		A,[usb_tx_flags]
	and		A,~TX_KBD_MASK                                    
    or     A,USB_REPORT_ERROR                      ; there's currently an error,
    mov     [usb_tx_flags],A
    mov     [usb_current_state],A                   ; mark as such
.exit:
    ret


;========================================================================
; FUNCTION:usbkey_putkey 
;
;handles key presses in usb environment.
;
; This function is called from within the key scanning loop, each time a
; valid key event has been recognized.  A key event is defined as whenever 
; an individual key changes state, either up or down.  the key is 
; identified by a unique number in the accumulator  from 1 to XXX, 
; where XXX is GENERALLY the corresponding AT101 keyboard number, with
; few execptions (see at101.inc).
;========================================================================


usbkey_putkey:
   call    usb_alternate_key
   jc     .done_putkey
    
    call    ksc_modifier                           ;check for a modifier
    jnc      .non_modifiers
    
	mov		A,[usb_tx_flags]
	and		A,~TX_KBD_MASK
 	or		A, USB_REPORT_KEY                      ; show that a report is required
	mov		[usb_tx_flags], A
    mov     A,[ksc_mod0]
    mov     [usb_last_mod],A
    jmp     .done_putkey

.non_modifiers:
    index   usb_usage_table
	push	X                                       ; save X on stack
	push	A                                       ; save key code on stack

	
	mov		A,[usb_tx_flags]
	and		A,~TX_KBD_MASK
	or		A, USB_REPORT_KEY                       ; show that a report is required
	mov		[usb_tx_flags], A

	mov		A, [ksc_down_up]
	cmp		A, 0
	jnz		.add_key_to_buffer				        ; key down
													; otherwise, key is up


.remove_key_from_buffer:                            ; key is up, so remove if from buffer
	mov		A, [usb_key_count]
	cmp		A, 0                                    ; decrement key count (unless it's 0)
	jz		.skip_decrement_key_count
	dec		[usb_key_count]
.skip_decrement_key_count:
	mov		X, 2
.find_key_in_buffer:                                ; find the key in the report buffer
	pop		A
	push	A
	cmp		A, [X + usb_report_buffer]
	jz		.clear_buffer_position
	inc		X
	mov		A, X
	cmp		A, 8
	jc		.find_key_in_buffer
	pop		A
	jmp		.non_modifiers_done                     ; done search

.clear_buffer_position:                             ; key found in buffer, so clear position
	pop		A
	mov		A, 0
	mov		[X + usb_report_buffer], A
	jmp		.non_modifiers_done

	
.add_key_to_buffer:                                 ; key went down, so put it in the buffer
	mov		A, [usb_key_count]
	cmp		A, FFh                                  ; increment key count (unless it's 255)
	jz		.skip_increment_key_count
	inc		[usb_key_count]
.skip_increment_key_count:
	mov		X, 2
.find_free_buffer_position:                         ; find a free buffer position
	mov		A, 0
	cmp		A, [X + usb_report_buffer]
	jz .put_key_in_buffer_position
	inc		X
	mov		A, X
	cmp		A, 8
	jc		.find_free_buffer_position
	pop		A
	jmp		.non_modifiers_done                     ; could not find a free position
						                            ; more than 6 keys pressed

.put_key_in_buffer_position:                        ; found a free buffer position, so put key code there
	pop		A
	mov		[X + usb_report_buffer], A

.non_modifiers_done:
	pop		X  

.done_putkey:
    ret  


    XPAGEOFF

;tables for alternate keys

;lookup table for special keys.  The keys in this table
;are treated differently.
alt_key_table:
    db      AT101KB_SLEEP,AT101KB_POWER,AT101KB_WAKE
	db		AT101KB_MUTE,AT101KB_VOL_INC,AT101KB_VOL_DEC,AT101KB_PLAY_PAUSE
	db		AT101KB_STOP,AT101KB_SCAN_PREV,AT101KB_SCAN_NEXT,AT101KB_EMAIL,
	db		AT101KB_CALCULATOR,AT101KB_WWW_SEARCH,AT101KB_WWW_HOME,AT101KB_WWW_FAVORITES

;each key above is represented in a report as a single bit -- 1 == pressed.
;this table contains the masks for the bits representing each key

bit_mask_table:
    db   1,2,4,
    db  1,2,4,8
	db  10h,20h,40h,80h
	db  1,2,4,8

;each key's bit mask must be applied to the data byte corresponding to it.
;this table points to the data byte's position in RAM.

pointer_table:
	db usb_power_keys,usb_power_keys,usb_power_keys,
	db usb_mm_keys,usb_mm_keys,usb_mm_keys,usb_mm_keys
	db usb_mm_keys,usb_mm_keys,usb_mm_keys,usb_mm_keys
	db usb_mm_keys+1,usb_mm_keys+1,usb_mm_keys+1,usb_mm_keys+1



    XPAGEON



NUM_POWER_KEYS:		equ 3
NUM_CONSUMER_KEYS:	equ 12
NUM_ALT_KEYS:    equ NUM_POWER_KEYS + NUM_CONSUMER_KEYS



;========================================================================
; FUNCTION:usb_power_key 
;
;handles power, sleep, and wake key presses in usb environment.
;
; This function was invented to trap the power, sleep, and wake key presses
; and maintain a single byte whose format is as follows:
;
; bit 1:  1 = power key pressed
; bit 2:  1 = sleep key pressed
; bit 3   1 = wake key pressed
;
; if any of these three keys changes state, the corresponding bit in the
; bit field is modified and the usb_power_flag is set to indicate that the
; state of the power keys has changed.
;========================================================================

usb_alternate_key:

    mov     [ksc_work],A                            ;store key in work byte
    mov     A,(NUM_ALT_KEYS - 1)                   ;initialize A to number of power keys
.lp1:
    push    A                                       ;save index
    index   alt_key_table							;get lookup
    cmp     A,[ksc_work]                            ;compare to key
    pop     A                                       ;restore index
    jz      .lp2                                    ;compare was a success, key found
    dec      A          
    jnc     .lp1									;
	CLEARC
	jmp		.exit									;done, get out

.lp2:
	;A contains index of found alternate key
	push	X										;save X
	push	A										;save index
	index   pointer_table							;get locale of buffer
	mov		X,A										;init X to buffer location
	pop		A										;retrieve index
	index	bit_mask_table							;now get bit mask into A
	push	A										;save it 
	mov		A, [ksc_down_up]						; depending on if key went
	cmp		A, 00h                                  ; up or down
	pop		A                                       ; restore bit pattern
	jz		.mod0_up                                ; key went down
	or		[X + 0], A                              ; set bit
	jmp		.done_putkey
.mod0_up:									        ; else, key went up
	cpl                                             ; so clear bit
	and		[X + 0], A       
.done_putkey:
	mov		A,X										;get buffer pointer
	cmp		A,usb_power_keys						;if pointing at power buffer,
	mov		A,TX_POWER_MASK							;set power flag
	jz		.set
	mov		A,TX_MM_MASK							;else set MM flag
.set:                                    
	pop		X										;restore X
    or     [usb_tx_flags],A							;set flag
    SETC											;set carry indicating key found
.exit:
	mov		A,[ksc_work]							;restore key code
 	ret												;and out


    


    XPAGEOFF

usb_usage_table:
	db			000h,035h,01eh,01fh,020h,021h,022h,023h	;0-7
	db			024h,025h,026h,027h,02dh,02eh,000h,02ah	;8-15
	db			02bh,014h,01ah,008h,015h,017h,01ch,018h	;16-23
	db			00ch,012h,013h,2fh,030h,031h,039h,004h	;24-31
	db			016h,007h,009h,00ah,00bh,00dh,00eh,00fh ;32-39
	db			033h,034h,032h,028h,0e1h,064h,01dh,01bh	;40-47
	db			006h,019h,005h,011h,010h,036h,037h,038h	;48-55
	db			000h,0e5h,0e0h,000h,0e2h,02ch,0e6h,000h	;56-63
	db			0e4h,000h,000h,000h,000h,000h,000h,000h ;64-71
	db			000h,000h,000h,049h,04ch,000h,000h,050h ;72-79
	db			04ah,04dh,000h,052h,051h,04bh,04eh,000h	;80-87
	db			000h,04fh,053h,05fh,05ch,059h,000h,054h	;88-95
	db			060h,05dh,05ah,062h,055h,061h,05eh,05bh	;96-103
	db			063h,056h,057h,000h,058h,000h,029h,000h	;104-111
	db			03ah,03bh,03ch,03dh,03eh,03fh,040h,041h	;112-119
	db			042h,043h,044h,045h,046h,047h,048h,0e3h	;120-127
	db			0e7h,065h,066h,067h,068h,000h,000h,000h	;128-235

    XPAGEON