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gcn64txrx: Return an error code specific to overflow

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This commit is contained in:
Raphael Assenat 2015-12-06 16:11:29 -05:00
parent 338c29f06c
commit 8fe9a98a11
2 changed files with 32 additions and 9 deletions
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39
gcn64txrx.S
View File

@ -49,7 +49,7 @@
; unsigned int gcn64_receiveBytes(unsigned char *dstbuf, unsigned char max_bytes);
; r24,r25 : dstbuf
; r22 : max bytes (for fututre use)
; return: count in r24,r25
; return: count in r24,r25 (0xff: Error, 0xfe: Overflow [max_bytes too low])
gcn64_receiveBytes:
clr xl
clr xh
@ -83,9 +83,9 @@ waitlow_lp:
rjmp waithigh
store_byte:
inc r24 ; Count byte
cp r22, r24
cp r22, r24 ; Check max_bytes
breq overflow
inc r24 ; Count byte
st z+,r20
ldi r20, 1
@ -98,18 +98,35 @@ waithigh_lp:
rjmp waithigh_lp
rjmp waitlow
overflow:
ser r24 ; 0xff
dec r24 ; 0xfe
ret
timeout:
tst r24
breq rxdone ; If r24 is still zero, we did not receive anything. Return 0.
; Otherwise, it is a frame error (i.e. A partial byte was received)
frame_error:
overflow: ; Treat overflow as an error as well
ser r24
rxdone:
; Return the number if received bits in r24
ret
; These are for a slower 4us/1.5us timing.
; The MadCatz Microcon does not work with 3us/1us timing...
#define LOOPS_SEND0_LOW 20
#define DELAY_SEND0_HIGH 2
#define LOOPS_SEND1_LOW 4
#define LOOPS_SEND1_HIGH 13
/*
; These are for the perfect 3us/1us timing described below
#define LOOPS_SEND0_LOW 15
#define LOOPS_SEND1_LOW 4
#define LOOPS_SEND1_HIGH 10
*/
/************************************************
* Send data using the N64/GC serial protocol which
* is as follows:
@ -157,7 +174,7 @@ send_next_bit:
send0:
sbi GCN64_DATA_DDR, GCN64_DATA_BIT ; Pull bus to 0
ldi r20, 15
ldi r20, LOOPS_SEND0_LOW
lp_send0_3us:
dec r20
brne lp_send0_3us
@ -165,6 +182,12 @@ lp_send0_3us:
cbi GCN64_DATA_DDR, GCN64_DATA_BIT ; Release bus to 1
#ifdef DELAY_SEND0_HIGH
ldi r20, DELAY_SEND0_HIGH
lp_send0_1us:
dec r20
brne lp_send0_1us
#endif
lsr r27
breq send_next_byte
@ -179,7 +202,7 @@ lp_send0_3us:
send1:
sbi GCN64_DATA_DDR, GCN64_DATA_BIT ; Pull bus to 0
ldi r20, 4
ldi r20, LOOPS_SEND1_LOW
lp_send1_1us:
dec r20
brne lp_send1_1us
@ -188,7 +211,7 @@ lp_send1_1us:
cbi GCN64_DATA_DDR, GCN64_DATA_BIT ; Release bus to 1
ldi r20, 10
ldi r20, LOOPS_SEND1_HIGH
lp_send1_3us:
dec r20
brne lp_send1_3us
@ -216,7 +239,7 @@ send_stop:
nop
; STOP BIT
sbi GCN64_DATA_DDR, GCN64_DATA_BIT ; Pull low for stop bit
ldi r20, 4
ldi r20, LOOPS_SEND1_LOW
stbdly0:
dec r20
brne stbdly0

2
gcn64txrx.h
View File

@ -7,7 +7,7 @@ void gcn64_sendBytes(const unsigned char *data, unsigned char n_bytes);
* \brief Receive up to \max_bytes bytes
* \param dstbuf Destination buffer
* \param max_bytes The maximum number of bytes
* \return The number of received bytes. 0xFF in case of error
* \return The number of received bytes. 0xFF in case of error, 0xFE in case of overflow (max_bytes too small)
*/
unsigned char gcn64_receiveBytes(unsigned char *dstbuf, unsigned char max_bytes);