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os-k/kaleid/libbuf/bscroll.c

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//----------------------------------------------------------------------------//
// GNU GPL OS/K //
// //
// Desc: Buffer library //
// //
// //
// Copyright © 2018-2020 The OS/K Team //
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// //
// This file is part of OS/K. //
// //
// OS/K is free software: you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation, either version 3 of the License, or //
// any later version. //
// //
// OS/K is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY//without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with OS/K. If not, see <https://www.gnu.org/licenses/>. //
//----------------------------------------------------------------------------//
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#include <lib/buf.h>
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void BEnableAutoScroll(Buffer_t *buf) { buf->flags |= BF_AUTOSCROLL; }
void BDisableAutoScroll(Buffer_t *buf) { buf->flags &= ~BF_AUTOSCROLL; }
error_t BScrollDownBuf(Buffer_t *buf)
{
error_t rc;
if (!buf) return EINVAL;
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if (!(buf->flags & BF_TERM)) return EBADF;
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if (buf->flags & (BF_EOF|BF_ERR)) return EENDF;
if (buf->state != BS_RDWR && buf->state != BS_WRONLY) {
return EBADF;
}
ExAcquireLock(&buf->lock);
rc = bscrolldown(buf);
ExReleaseLock(&buf->lock);
return rc;
}
error_t bscrolldown(Buffer_t *buf)
{
size_t bufSize, pbCount;
assert(buf->wp == buf->buf + buf->size);
// We give up a whole playback buffer worth
// of lines so we don't have to do this too often
// (we make the current buffer a pb one)
bufSize = buf->nLines * buf->lineLen;
pbCount = (buf->size / bufSize) - 1;
// Paranoia check
assert(buf->size >= (size_t)(buf->nLines * buf->lineLen));
// If we only have one playback buffer we just give up a line
if (pbCount == 0) {
// Use of memcpy() is safe because the source occur
// after the destination
memmove(buf->buf, buf->buf + buf->lineLen,
buf->size - buf->lineLen);
buf->wp -= buf->lineLen;
}
// We do have a playback buffer worth of lines to give up
else {
memmove(buf->buf, buf->buf + bufSize,
buf->size - bufSize);
buf->wp -= bufSize;
}
return EOK;
}