219 lines
6.4 KiB
Plaintext
219 lines
6.4 KiB
Plaintext
;;********************************************************************************
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;; @module ps2_keyboard
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;; @ingroup drivers
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;; @details:
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;; Support for a PS2 Keyboard using the shift register of a 6522 VIA
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;; @section reading Reading a scancode/command answer
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;; Pressing a key causes 11 bits to be sent: 1 start - 8 scancode - 1 parity - 1 stop
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;; The VIA is set up to interrupt after 8 bits have been shifted into the shift register
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;; from the external clock pulses of the keyboard (additional hardware required to
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;; address the hardware bug of the VIA, where bit get lost when the external clock
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;; transition happens during falling edge of PHI2). After reading the shift register,
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;; the VIAs T2 timer is set to interrupt after the last 3 bits have been shifted in,
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;; which takes about ~230ms.
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;; T2 is used because it leaves to more versatile T1 available for something else
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;;
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;; @section processing Processing a scancode
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;; The scancode may be processed by storing the address of a handler subroutine in
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;; `ps2kb::scancode_handler`. This handler can load the scancode byte from `ps2kb::scancode`.
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;;
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;; To use a different layout, change the enum K and the CHARS_NOMOD and CHARS_MODSHIFT
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;; @warning
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;; The value with which the timer is loaded must depends on the clock frequency
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;; of the keyboard and the computer
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;;********************************************************************************
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.ifndef INCLUDE_PS2_KEYBOARD
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INCLUDE_PS2_KEYBOARD = 1
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.include "system.h65"
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;;********************************************************************************
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;; @brief PS/2 Keyboard
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;; This requires the data line to be hooked up to `CB2` and the clock to `CB1`.
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;; The VIA will be set to shift in the data into the shift register under the external clock.
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;; @see @ref via_hardware_bug "VIA external clock bug"
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;; @include keyboard
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;; @ingroup drivers
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;;********************************************************************************
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.scope ps2kb
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Import ps2kb, init, begin_receive, scancode, status, scancode_handler
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Import ps2kb, _receive_irq_shift_reg_handler, _receive_irq_timer_handler, _send_byte, _send_irq_shift_reg_handler, _send_irq_timer_handler,
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Import ps2kb, send_command, send_cmd, send_data, cmd_response, response_length, FMT_CMD_FAIL
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;; Base address of the VIA the keyboard is conencted to
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VIA = IO1
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;; @brief #clock cycles to to wait for the last 3 bits after the first 8 have been shifted in
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;; @details
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;; The last 3 bits take about 230 ms.
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;; Calculate the appropriate value using: @f$ N_\text{cycles} = 230 \times f_\text{in MHZ} @f$
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;; - 230 \@ 1MHz
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;; - 400 \@ 1.84 MHz
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;; @clock_dependant
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TIMER_RECV = 400
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;; @brief #clock cycles to wait after loading the SR a second time while sending a command to the keyboard
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;; @details
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;; Enough time must pass for one bit must be shifted out (parity),
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;; but at most two (parity+stop).
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;; After that, the interrupt must have happened because the keyboard will pull data low.
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;; At that point, the shift register needs to be set to input again
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;;
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;; Values that seem to work:
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;; - 230 \@ 1MHz
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;; - 400 \@ 1.84 MHz
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;; @clock_dependant
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TIMER_SEND = 400
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PULL_REG = IO::RANH
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PULL_DDR = IO::DDRA
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; use RA4 to pull the clock low
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PULL_MASK_CLK = %00010000
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; using ff because 0 is a possible data byte (set led)
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NO_DATA = $ff ;; indicates that no data byte should be send
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NO_RESPONSE = $ff ;; indicates a command did not receive a response (yet)
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ACK = $fa ;; successful transmission
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RESEND = $fe ;; unsuccessful transmission
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.enum STATUS
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RECEIVE_KEYS = %10000000 ;; keyboard sends scancodes
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RECEIVE_ANSWER = %01000000 ;; keyboard replies to a command
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SEND_CMD = %00100000 ;; host sends/sent the command byte
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SEND_DATA = %00010000 ;; host sends/sent the data byte
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SEND_RECV = %00001000 ;; keyboard sends additional data byte
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SEND = SEND_CMD | SEND_DATA | SEND_RECV ;; host is sending something, only used for checking status
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NONE = %00000000
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.endenum
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.enum TYPEMATIC
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REPEAT_MASK = %00011111 ;; 00000 = 30Hz, ..., 11111 = 2Hz
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DELAY250 = %00000000
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DELAY500 = %00100000
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DELAY750 = %01000000
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DELAY1000 = %01100000
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.endenum
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.endscope
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; see https://wiki.osdev.org/PS/2_Keyboard
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.macro ps2kb_CmdEcho
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lda #$ee
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ldx #ps2kb::NO_DATA
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSetLeds mask
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lda #$ed
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.ifnblank mask
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ldx #mask
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.endif
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdGetScancodeSet
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lda #$f0
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ldx #0
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ldy #1
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSetScancodeSet set
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.assert set = 1 .or set = 2 .or set = 3, warning, "ps2kb_CmdSetScancodeSet: invalid scancode set"
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lda #$f0
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ldx #set
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdIdentify
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lda #$f2
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ldx #ps2kb::NO_DATA
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ldy #2
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdTypematicSettings settings
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lda #$f3
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ldx #settings
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdEnable
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lda #$f4
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ldx #ps2kb::NO_DATA
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdDisable
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lda #$f5
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ldx #ps2kb::NO_DATA
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ldy #0
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSetTypematic scancode
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ldy #0
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.ifblank scancode
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lda #$f7
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ldx #ps2kb::NO_DATA
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.else
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lda #$fb
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ldx #scancode
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.endif
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSetMakeRelease scancode
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ldy #0
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.ifblank scancode
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lda #$f8
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ldx #ps2kb::NO_DATA
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.else
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lda #$fc
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ldx #scancode
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.endif
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSetMake scancode
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ldy #0
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.ifblank scancode
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lda #$f9
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ldx #ps2kb::NO_DATA
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.else
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lda #$fd
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ldx #scancode
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.endif
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_CmdSelfTest
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lda #$ff
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ldx #ps2kb::NO_DATA
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ldy #1
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jsr ps2kb::send_command
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.endmacro
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.macro ps2kb_WaitFinishCmd
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:
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wai
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lda ps2kb::status
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and #ps2kb::STATUS::SEND
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bne :-
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.endmacro
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;;********************************************************************************
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;; @note You need to manually include `string.h65` when using this macro!
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;;********************************************************************************
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.macro ps2kb_PrintCmdFailed
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Printf ps2kb::FMT_CMD_FAIL,ps2kb::send_cmd,ps2kb::send_data,ps2kb::cmd_response,ps2kb::cmd_response+1,ps2kb::cmd_response+2
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.endmacro
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.endif ; guard
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