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ymodem: refactor _rym_read_code 

Make fast path fast and slow path slow.
This commit is contained in:
Grissiom 2014-07-13 18:26:48 +08:00
parent 64a2902fa9
commit ff1eb2cbc9
1 changed files with 15 additions and 10 deletions
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19
components/utilities/ymodem/ymodem.c
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@ -70,18 +70,23 @@ static enum rym_code _rym_read_code(
struct rym_ctx *ctx,
rt_tick_t timeout)
{
/* consume the available sem and read the data in buffer if possible */
while (rt_sem_trytake(&ctx->sem) == RT_EOK)
;
/* Fast path */
if (rt_device_read(ctx->dev, 0, ctx->buf, 1) == 1)
return *ctx->buf;
/* no data yet, wait for one */
/* Slow path */
do {
rt_size_t rsz;
/* No data yet, wait for one */
if (rt_sem_take(&ctx->sem, timeout) != RT_EOK)
return RYM_CODE_NONE;
/* read one */
if (rt_device_read(ctx->dev, 0, ctx->buf, 1) == 1)
/* Try to read one */
rsz = rt_device_read(ctx->dev, 0, ctx->buf, 1);
if (rsz == 1)
return *ctx->buf;
return RYM_CODE_NONE;
} while (1);
}
/* the caller should at least alloc _RYM_STX_PKG_SZ buffer */