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swd: Improve parity calculation and move it to types.h

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It could be reused by SWD drivers and in other places.

Change-Id: Ieed0cf70c111a73d3a42ed59f46a0cdd177a73d5
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1957
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>
This commit is contained in:
Andreas Fritiofson
2014-02-17 00:27:09 +01:00
parent 0e95ec4070
commit 36772a7ed0
2 changed files with 20 additions and 12 deletions
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13
src/jtag/swd.h
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@@ -32,17 +32,6 @@
#define SWD_CMD_PARK (0 << 7) /* not driven by host (pull high) */
/* followed by TRN, 3-bits of ACK, TRN */
/* pbit16 holds precomputed parity bits for each nibble */
#define pbit(parity, nibble) ((parity) << (nibble))
static const uint16_t pbit16 =
pbit(0, 0) | pbit(1, 1) | pbit(1, 2) | pbit(0, 3)
| pbit(1, 4) | pbit(0, 5) | pbit(0, 6) | pbit(1, 7)
| pbit(1, 8) | pbit(0, 9) | pbit(0, 0xa) | pbit(1, 0xb)
| pbit(0, 0xc) | pbit(1, 0xd) | pbit(1, 0xe) | pbit(0, 0xf);
#define nibble_parity(nibble) (pbit16 & pbit(1, (nibble)))
/**
* Construct a "cmd" byte, in lSB bit order, which swd_driver.read_reg()
* and swd_driver.write_reg() methods will use directly.
@@ -54,7 +43,7 @@ static inline uint8_t swd_cmd(bool is_read, bool is_ap, uint8_t regnum)
| ((regnum & 0xc) << 1);
/* 8 cmd bits 4:1 may be set */
if (nibble_parity(cmd >> 1))
if (parity_u32(cmd))
cmd |= SWD_CMD_PARITY;
/* driver handles START, STOP, and TRN */