Low-level helpers for orthogonal rotation. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "allheaders.h"

Functions
void	rotate90Low (l_uint32 datad, l_int32 wd, l_int32 hd, l_int32 d, l_int32 wpld, l_uint32 datas, l_int32 wpls, l_int32 direction)
void	flipLRLow (l_uint32 data, l_int32 w, l_int32 h, l_int32 d, l_int32 wpl, l_uint8 tab, l_uint32 *buffer)
void	flipTBLow (l_uint32 data, l_int32 h, l_int32 wpl, l_uint32 buffer)
l_uint8 *	makeReverseByteTab1 (void)
l_uint8 *	makeReverseByteTab2 (void)
l_uint8 *	makeReverseByteTab4 (void)

Detailed Description

Low-level helpers for orthogonal rotation.

    90-degree rotation (cw)
          void      rotate90Low()

    LR-flip
          void      flipLRLow()

    TB-flip
          void      flipTBLow()

    Byte reverse tables
          l_uint8  *makeReverseByteTab1()
          l_uint8  *makeReverseByteTab2()
          l_uint8  *makeReverseByteTab4()

Definition in file rotateorthlow.c.

Function Documentation

void rotate90Low	(	l_uint32 *	datad,
		l_int32	wd,
		l_int32	hd,
		l_int32	d,
		l_int32	wpld,
		l_uint32 *	datas,
		l_int32	wpls,
		l_int32	direction
	)

rotate90Low()

direction: 1 for cw rotation -1 for ccw rotation

Notes: (1) The dest must be cleared in advance because not all source pixels are written to the destination.

Definition at line 56 of file rotateorthlow.c.

References GET_DATA_BIT, GET_DATA_BYTE, GET_DATA_DIBIT, GET_DATA_QBIT, GET_DATA_TWO_BYTES, L_ERROR, PROCNAME, SET_DATA_BIT, SET_DATA_BYTE, SET_DATA_DIBIT, SET_DATA_QBIT, and SET_DATA_TWO_BYTES.

Referenced by pixRotate90().

void flipLRLow	(	l_uint32 *	data,
		l_int32	w,
		l_int32	h,
		l_int32	d,
		l_int32	wpl,
		l_uint8 *	tab,
		l_uint32 *	buffer
	)

flipLRLow()

Notes: (1) The pixel access routines allow a trivial implementation. However, for d < 8, it is more efficient to right-justify each line to a 32-bit boundary and then extract bytes and do pixel reversing. In those cases, as in the 180 degree rotation, we right-shift the data (if necessary) to right-justify on the 32 bit boundary, and then read the bytes off each raster line in reverse order, reversing the pixels in each byte using a table. These functions for 1, 2 and 4 bpp were tested against the "trivial" version (shown here for 4 bpp): for (i = 0; i < h; i++) { line = data + i * wpl; memcpy(buffer, line, bpl); for (j = 0; j < w; j++) { val = GET_DATA_QBIT(buffer, w - 1 - j); SET_DATA_QBIT(line, j, val); } } (2) This operation is in-place.

Definition at line 280 of file rotateorthlow.c.

References GET_DATA_BYTE, GET_DATA_TWO_BYTES, L_ERROR, PROCNAME, rasteropHipLow(), SET_DATA_BYTE, and SET_DATA_TWO_BYTES.

Referenced by pixFlipLR().

void flipTBLow	(	l_uint32 *	data,
		l_int32	h,
		l_int32	wpl,
		l_uint32 *	buffer
	)

flipTBLow()

Notes: (1) This is simple and fast. We use the memcpy function to do all the work on aligned data, regardless of pixel depth. (2) This operation is in-place.

Definition at line 404 of file rotateorthlow.c.

Referenced by pixFlipTB().

l_uint8* makeReverseByteTab1 ( void )

makeReverseByteTab1()

Notes: (1) This generates an 8 bit lookup table for reversing the order of eight 1-bit pixels.

Definition at line 437 of file rotateorthlow.c.

References CALLOC, ERROR_PTR, NULL, and PROCNAME.

Referenced by pixFlipLR().

l_uint8* makeReverseByteTab2 ( void )

makeReverseByteTab2()

Notes: (1) This generates an 8 bit lookup table for reversing the order of four 2-bit pixels.

Definition at line 469 of file rotateorthlow.c.