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ibmpc: Refactor code

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This commit is contained in:
tmk 2020-01-24 23:19:18 +09:00
parent 4588ae8dac
commit 2f640de68d
1 changed files with 41 additions and 40 deletions
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81
tmk_core/protocol/ibmpc.c
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@ -68,7 +68,7 @@ volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
*/
static volatile uint16_t recv_data = 0xFFFF;
/* internal state of receiving data */
static volatile uint16_t isr_data = 0x8000;
static volatile uint16_t isr_state = 0x8000;
void ibmpc_host_init(void)
{
@ -194,7 +194,7 @@ int16_t ibmpc_host_recv_response(void)
void ibmpc_host_isr_clear(void)
{
isr_data = 0x8000;
isr_state = 0x8000;
recv_data = 0xFFFF;
}
@ -205,50 +205,47 @@ ISR(IBMPC_INT_VECT)
{
uint8_t dbit;
dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
PINB|=0x01;
isr_data = isr_data>>1;
if (dbit) isr_data |= 0x8000;
isr_state = isr_state>>1;
if (dbit) isr_state |= 0x8000;
// isr_data: state of receiving data from keyboard
// isr_state: state of receiving data from keyboard
// This is initialized with 0x8000 before start receiving data and MSB '1' of
// the initial value is marker bit to discrimitate between protocols.
// It stores sampled bit at MSB after right shift on each clock falling edge.
//
// 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
// -----------------------------------------------------
// Initial: *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 MSB sentinel
// XT IBM: b7 b6 b5 b4 b3 b2 b1 b0 | s1 s0 *1 0 0 0 0 0 after receiving **
// XT Clone: b7 b6 b5 b4 b3 b2 b1 b0 | s1 *1 0 0 0 0 0 0 after receiving
// AT: st pr b7 b6 b5 b4 b3 b2 | b1 b0 s0 *1 0 0 0 0 after receiving
// AT**: pr b7 b6 b5 b4 b3 b2 b1 | b0 s0 *1 0 0 0 0 0 before stop bit **
// Initial: *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 with MSB marker *1
// XT_Type-1: b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 start bit 0 and 1 **
// XT_Type-2: b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 start bit 1
// AT: st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 start bit 0
// AT**: pr b7 b6 b5 b4 b3 b2 b1 | b0 0 *1 0 0 0 0 0 before stop bit **
//
// x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
// x x x x x x x x | 1 0 0 0 0 0 0 0 midway(8 bits received)
// x x x x x x x x | 0 1 0 0 0 0 0 0 XT IBM-midway or AT-midway
// x x x x x x x x | 1 1 0 0 0 0 0 0 XT Clone-done
// x x x x x x x x | 0 0 1 0 0 0 0 0 AT-midway
// x x x x x x x x | 1 0 1 0 0 0 0 0 XT IBM-done or AT-midway **
// x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
// x x x x x x x x | 0 *1 0 0 0 0 0 0 XT_Type1-midway or AT-midway
// x x x x x x x x | 1 *1 0 0 0 0 0 0 XT_Type2-done
// x x x x x x x x | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
// x x x x x x x x | 1 0 *1 0 0 0 0 0 XT_Type1-done or AT-midway[b0=1]
// x x x x x x x x | x 1 1 0 0 0 0 0 illegal
// x x x x x x x x | x x 0 1 0 0 0 0 AT-done
// x x x x x x x x | x x 1 1 0 0 0 0 illegal
// other states than avobe illegal
// other states than above illegal
//
// **: AT can take same as end sate of XT IBM(1010 000) when b0 is 1,
// to discriminate between them we will have to wait a while for stop bit.
//
// mask for isr_data:
// 0x00A0(1010 0000) when XT IBM
// 0x00C0(1100 0000) when XT Clone
// 0x0010(xx01 0000) when AT
//
switch (isr_data & 0xFF) {
// **: AT takes same state as XT_Type1-done(1010 000) in case that AT b0 is 1,
// to discriminate between the two protocol we will have to wait a while for AT stop bit.
switch (isr_state & 0xFF) {
case 0b00000000:
case 0b10000000:
case 0b01000000:
case 0b00100000:
// midway
return;
goto NEXT;
break;
case 0b11000000:
// XT Clone-done
// XT_Type2-done
recv_data = recv_data<<8;
recv_data |= (isr_data>>8) & 0xFF;
recv_data |= (isr_state>>8) & 0xFF;
goto DONE;
break;
case 0b10100000:
@ -259,14 +256,12 @@ PINB|=0x01;
while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
if (us) {
// found stop bit: return immediately and process the stop bit in ISR
// AT-midway
return;
// found stop bit: AT-midway - process the stop bit in next ISR
goto NEXT;
} else {
// no stop bit
// XT-IBM-done
// no stop bit: XT_Type1-done
recv_data = recv_data<<8;
recv_data |= (isr_data>>8) & 0xFF;
recv_data |= (isr_state>>8) & 0xFF;
goto DONE;
}
}
@ -277,7 +272,7 @@ PINB|=0x01;
case 0b11010000:
// AT-done
recv_data = recv_data<<8;
recv_data |= (isr_data>>6) & 0xFF;
recv_data |= (isr_state>>6) & 0xFF;
goto DONE;
break;
case 0b01100000:
@ -287,14 +282,20 @@ PINB|=0x01;
case 0b01110000:
case 0b11110000:
default: // xxxx_oooo(any 1 in low nibble)
recv_data = isr_data;
// Illegal
goto ERROR;
break;
}
ERROR:
isr_state = 0x8000;
recv_data = 0xFF00; // clear data and scancode of error 0x00
ibmpc_error = 0xFF;
return;
DONE:
// TODO: check protocol change to support keyboard howswap
// not correct if there is clock edge within short time like 100us after receving data
// TODO: process error code: 0x00(AT), 0xFF(XT) in particular
isr_data = 0x8000; // clear to next data
isr_state = 0x8000; // clear to next data
NEXT:
return;
}