/* sane - Scanner Access Now Easy.

   pieusb_buffer.c

   Copyright (C) 2012-2015 Jan Vleeshouwers, Michael Rickmann, Klaus Kaempf

   This file is part of the SANE package.

   This program 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 2 of the
   License, or (at your option) any later version.

   This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.

   As a special exception, the authors of SANE give permission for
   additional uses of the libraries contained in this release of SANE.

   The exception is that, if you link a SANE library with other files
   to produce an executable, this does not by itself cause the
   resulting executable to be covered by the GNU General Public
   License.  Your use of that executable is in no way restricted on
   account of linking the SANE library code into it.

   This exception does not, however, invalidate any other reasons why
   the executable file might be covered by the GNU General Public
   License.

   If you submit changes to SANE to the maintainers to be included in
   a subsequent release, you agree by submitting the changes that
   those changes may be distributed with this exception intact.

   If you write modifications of your own for SANE, it is your choice
   whether to permit this exception to apply to your modifications.
   If you do not wish that, delete this exception notice.  */

/* =========================================================================
 *
 * Read buffer
 *
 * Data obtained from the scanner cannot be presented to the frontend immediately.
 * The scanner returns data in the 'index' or 'line' color format, which means it
 * returns data in batches which contain a single color of a scan line.
 *
 * These must finally be converted into the SANE data format (data for a single
 * pixel in consecutive bytes). Apart from that, sane_read() must be able to
 * return any amount of data bytes.
 *
 * In between, data processing may be necessary, usually requiring the whole
 * image to be available.
 *
 * To accommodate all this, the buffer stores all samples as 16-bit values, even
 * if the original values are 8-bit or even 1 bit. This is a waste of space, but
 * makes processing much easier, and it is only temporary.
 *
 * The read buffer is constructed by a call to buffer_create(), which initializes
 * the buffer based on width, height, number of colors and depth. The buffer
 * contains data organized in color planes, with each plane consisting of lines,
 * each line of a fixed number of (single color) pixels, and each pixel of a fixed
 * number of bits (or bytes).
 *
 * The buffer maintains read and write pointers.
 *
 * Multi-color data with a bit depth of 1 are packed in single color bytes, so
 * the data obtained from the scanner does not need conversion.
 *
 * ========================================================================= */

#define DEBUG_DECLARE_ONLY

/* Configuration defines */
#include "../include/sane/config.h"

/* SANE includes */
#include "../include/sane/sane.h"
#include "../include/sane/saneopts.h"
#include "../include/sane/sanei_usb.h"
#include "../include/sane/sanei_config.h"

/* Backend includes */
#define BACKEND_NAME pieusb
#include "../include/sane/sanei_backend.h"
#include "pieusb.h"

#include "pieusb_specific.h"
#include "pieusb_buffer.h"

#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif

#include <stdio.h>
#include <fcntl.h>
#include <sys/mman.h>

#include "byteorder.h"

static void buffer_update_read_index(struct Pieusb_Read_Buffer* buffer, int increment);

/* READER */

/**
 * Initialize the buffer.
 * A scanner has a Pieusb_Read_Buffer struct as one of its members.
 *
 * @param buffer the buffer to initialize
 * @param width number of pixels on a line (row)
 * @param height number of lines in the buffer (pixels in a column)
 * @param colors bitmap specifying the colors in the scanned data (bitmap: 0000 IBGR)
 * @param depth number of bits of a color
 * @param bigendian how to store multi-byte values: bigendian if true
 * @param maximum_size maximum size of buffer (-1 = size of image)
 */

SANE_Status
sanei_pieusb_buffer_create(struct Pieusb_Read_Buffer* buffer, SANE_Int width, SANE_Int height, SANE_Byte color_spec, SANE_Byte depth)
{
    int k, result;
    unsigned int buffer_size_bytes;
    unsigned char g;

    /* Base parameters */
    buffer->width = width;
    buffer->height = height;
    buffer->colors = 0;
    if (color_spec & 0x01) { buffer->color_index_red = 0; buffer->colors++; } else { buffer->color_index_red = -1; }
    if (color_spec & 0x02) { buffer->color_index_green = 1; buffer->colors++; } else { buffer->color_index_green = -1; }
    if (color_spec & 0x04) { buffer->color_index_blue = 2; buffer->colors++; } else { buffer->color_index_blue = -1; }
    if (color_spec & 0x08) { buffer->color_index_infrared = 3; buffer->colors++; } else { buffer->color_index_infrared = -1; }
    if (buffer->colors == 0) {
        DBG(DBG_error, "sanei_pieusb_buffer_create(): no colors specified\n");
        return SANE_STATUS_INVAL;
    }
    buffer->depth = depth;
    if (depth < 1 || depth > 16) {
        DBG(DBG_error, "sanei_pieusb_buffer_create(): unsupported depth %d\n", depth);
        return SANE_STATUS_INVAL;
    }
    buffer->packing_density = (depth == 1) ? 8 : 1; /* These are all the situations we have */

    /* Derived*/
    buffer->packet_size_bytes = (buffer->depth * buffer->packing_density + 7) / 8;
    buffer->line_size_packets = (buffer->width + buffer->packing_density -1) / buffer->packing_density;
    buffer->line_size_bytes = buffer->line_size_packets * buffer->packet_size_bytes;
    buffer->image_size_bytes = buffer->colors * buffer->height * buffer->line_size_bytes;

    /* Create empty file */
    snprintf(buffer->buffer_name, L_tmpnam, "/tmp/sane.XXXXXX");
    if (buffer->data_file != 0) /* might still be open from previous invocation */
      close(buffer->data_file);
    buffer->data_file = mkstemp(buffer->buffer_name);
    if (buffer->data_file == -1) {
        buffer->data_file = 0;
        buffer->data = NULL;
	perror("sanei_pieusb_buffer_create(): error opening image buffer file");
        return SANE_STATUS_IO_ERROR;
    }
    /* Stretch the file size */
    buffer_size_bytes = buffer->width * buffer->height * buffer->colors * sizeof(SANE_Uint);
    if (buffer_size_bytes == 0) {
        close(buffer->data_file);
        buffer->data_file = 0;
        DBG(DBG_error, "sanei_pieusb_buffer_create(): buffer_size is zero: width %d, height %d, colors %d\n", buffer->width, buffer->height, buffer->colors);
        return SANE_STATUS_INVAL;
    }
    result = lseek(buffer->data_file, buffer_size_bytes-1, SEEK_SET);
    if (result == -1) {
	close(buffer->data_file);
        buffer->data_file = 0;
        buffer->data = NULL;
        DBG(DBG_error, "sanei_pieusb_buffer_create(): error calling lseek() to 'stretch' the file to %d bytes\n", buffer_size_bytes-1);
	perror("sanei_pieusb_buffer_create(): error calling lseek()");
        return SANE_STATUS_INVAL;
    }
    /* Write one byte at the end */
    g = 0x00;
    result = write(buffer->data_file, &g, 1);
    if (result < 0) {
	close(buffer->data_file);
        buffer->data_file = 0;
        buffer->data = NULL;
	perror("sanei_pieusb_buffer_create(): error writing a byte at the end of the file");
        return SANE_STATUS_IO_ERROR;
    }
#ifdef HAVE_MMAP
    /* Create memory map */
    buffer->data = mmap(NULL, buffer_size_bytes, PROT_WRITE | PROT_READ, MAP_SHARED, buffer->data_file, 0);
    if (buffer->data == MAP_FAILED) {
        close(buffer->data_file);
        buffer->data = NULL;
        perror("sanei_pieusb_buffer_create(): error mapping file");
        return SANE_STATUS_INVAL;
    }
#else
#error mmap(2) not available, aborting
#endif
    buffer->data_size = buffer_size_bytes;
    /* Reading and writing */
    buffer->p_read = calloc(buffer->colors, sizeof(SANE_Uint*));
    if (buffer->p_read == NULL)
      return SANE_STATUS_NO_MEM;
    buffer->p_write = calloc(buffer->colors, sizeof(SANE_Uint*));
    if (buffer->p_write == NULL)
      return SANE_STATUS_NO_MEM;
    for (k = 0; k < buffer->colors; k++) {
        buffer->p_write[k] = buffer->data + k * buffer->height * buffer->width;
        buffer->p_read[k] = buffer->p_write[k];
    }
    buffer->read_index[0] = 0;
    buffer->read_index[1] = 0;
    buffer->read_index[2] = 0;
    buffer->read_index[3] = 0;

    /* Statistics */
    buffer->bytes_read = 0;
    buffer->bytes_written = 0;
    buffer->bytes_unread = 0;

    DBG(DBG_info,"pieusb: Read buffer created: w=%d h=%d ncol=%d depth=%d in file %s\n",
      buffer->width, buffer->height, buffer->colors, buffer->depth, buffer->buffer_name);
  return SANE_STATUS_GOOD;
}

/**
 * Delete buffer and free its resources
 *
 * @param buffer
 */
void
sanei_pieusb_buffer_delete(struct Pieusb_Read_Buffer* buffer)
{
#ifdef HAVE_MMAP
    munmap(buffer->data, buffer->data_size);
#else
#error mmap(2) not available, aborting
#endif
    /* ftruncate(buffer->data_file,0); Can we delete given a file-descriptor? */
    close(buffer->data_file);
    /* remove fs entry */
    unlink(buffer->buffer_name);
    buffer->data_file = 0;
    buffer->data_size = 0;
    free(buffer->p_read);
    free(buffer->p_write);
    buffer->data = 0;
    buffer->width = 0;
    buffer->height = 0;
    buffer->depth = 0;
    buffer->colors = 0;
    buffer->packing_density = 0;

    DBG(DBG_info,"pieusb: Read buffer deleted\n");
}

/**
 * Add a line to the reader buffer, for the given color.
 * The buffer checks and decides how to interpret the data.
 *
 * @param buffer
 * @param color Color code for line
 * @param line
 * @param size Number of bytes in line
 * @return 1 if successful, 0 if not
 */
SANE_Int
sanei_pieusb_buffer_put_single_color_line(struct Pieusb_Read_Buffer* buffer, SANE_Byte color, void* line, SANE_Int size)
{

    SANE_Int c, k, m, n;

    /* Check index code */
    c = -1;
    switch (color) {
        case 'R':
            c = buffer->color_index_red;
            break;
        case 'G':
            c = buffer->color_index_green;
            break;
        case 'B':
            c = buffer->color_index_blue;
            break;
        case 'I':
            c = buffer->color_index_infrared;
            break;
    }
    if (c == -1) {
        DBG(DBG_error, "sanei_pieusb_buffer_put_single_color_line(): color '%c' not specified when buffer was created\n", color);
        return 0;
    }
    DBG(DBG_info_buffer, "sanei_pieusb_buffer_put_single_color_line() line color = %d (0=R, 1=G, 2=B, 3=I)\n",c);

    /* Check line size (for a line with a single color) */
    if (buffer->line_size_bytes != size) {
        DBG(DBG_error, "sanei_pieusb_buffer_put_single_color_line(): incorrect line size, expecting %d, got %d\n", buffer->line_size_bytes, size);
        return 0;
    }

    /* The general approach for all densities and packet sizes
     * - process packet_size_bytes at a time
     * - use packing_density to decode the full packet into separate values
     * - now save these values as neighbouring pixels on the current line
     * Use custom code for the 1-byte and 2-byte single sample cases,
     * because the general approach is a bit overkill for them.
     */

    if (buffer->packet_size_bytes == 1 && buffer->packing_density == 1) {
        uint8_t* p_packet = (uint8_t*)line;
        n = 0;
        while (n < size) {
            /* Get next packet data & store in buffer */
            *buffer->p_write[c]++ = *p_packet++;
            n++;
        }
    } else if (buffer->packet_size_bytes == 2 && buffer->packing_density == 1) {
        uint16_t* p_packet = (uint16_t*)line;
        n = 0;
        while (n < size) {
            /* Get next packet data & store in buffer */
            *buffer->p_write[c]++ = le16toh (*p_packet++);
            n += 2;
        }
    } else {
        uint8_t* p_packet = (uint8_t*)line;
        uint8_t *packet = (uint8_t *)alloca(buffer->packet_size_bytes * sizeof(uint8_t));
        SANE_Uint val;
        uint8_t mask = ~(0xFF >> buffer->depth); /* byte with depth most significant bits set */
        n = 0;
        while (n < size) {
            /* Get next packet data */
            for (k = 0; k < buffer->packet_size_bytes; k++) packet[k] = *p_packet++;
            /* Unpack packing_density samples from packet. Of course,
             * buffer->depth * packing_density <= # bits in packet.
             * That is checked at buffer creation. */
            for (k = 0; k < buffer->packing_density; k++) {
                /* Take 1st depth bits and store in val */
                val = (packet[0] & mask) >> (8-buffer->depth);
                /* Now shift packet bytes depth bits left */
                for (m = 0; m < buffer->packet_size_bytes; m++) {
                    /* Shift left one sample */
                    packet[m] <<= buffer->depth;
                    if (m < buffer->packet_size_bytes-1) {
                        /* If there are more bytes, insert 1st depth bits of next byte */
                        packet[m] |= (packet[m+1] >> (8-buffer->depth));
                    }
                }
                /* Store in buffer */
                *buffer->p_write[c]++ = val;
            }
            n += buffer->packet_size_bytes;
        }
    }

    /* Update state & statistics */
    buffer->bytes_written += size;
    buffer->bytes_unread += size;

    /* Output current buffer state */
    /* buffer_output_state(buffer); */

    return 1;
}

/**
 * Write line of full color pixels to the buffer.
 *
 * @param buffer Read buffer
 * @param pixel array of full color pixel data
 * @param size Number of bytes in the line
 * @return 1 if successful, 0 if not
 */
/**
 *
 */
SANE_Int
sanei_pieusb_buffer_put_full_color_line(struct Pieusb_Read_Buffer* buffer, void* line, int size)
{
    int k, c, m, n;

    DBG(DBG_info_buffer, "sanei_pieusb_buffer_put_full_color_line() entered\n");

    /* Check line size */
    if (buffer->line_size_bytes * buffer->colors != size) {
        DBG(DBG_error, "sanei_pieusb_buffer_put_full_color_line(): incorrect line size, expecting %d, got %d\n", buffer->line_size_bytes * buffer->colors, size);
        return 0;
    }

    /* The general approach for all densities and packet sizes
     * - process packet_size_bytes at a time
     * - use packing_density to decode the full packet into separate values
     * - now save these values as neighbouring pixels on the current line
     * Use custom code for the 1-byte and 2-byte single sample cases,
     * because the general approach is a bit overkill for them.
     */

    if (buffer->packet_size_bytes == 1 && buffer->packing_density == 1) {
        uint8_t* p_packet = (uint8_t*)line;
        n = 0;
        while (n < size) {
            /* Get next packet data & store in buffer */
            for (c = 0; c < buffer->colors; c++) {
                *buffer->p_write[c]++ = *p_packet++;
                n++;
            }
        }
    } else if (buffer->packet_size_bytes == 2 && buffer->packing_density == 1) {
        uint16_t* p_packet = (uint16_t*)line;
        n = 0;
        while (n < size) {
            /* Get next packet data & store in buffer */
            for (c = 0; c < buffer->colors; c++) {
                *buffer->p_write[c]++ = le16toh (*p_packet++);
                n += 2;
            }
        }
    } else {
        uint8_t* p_packet = (uint8_t*)line;
        uint8_t *packet = (uint8_t *)alloca(buffer->packet_size_bytes * sizeof(uint8_t));
        SANE_Uint val;
        uint8_t mask = ~(0xFF >> buffer->depth); /* byte with depth most significant bits set */
        /* DBG(DBG_info,"buffer_put_full_color_line(): mask %02x\n",mask); */
        n = 0;
        while (n < size) {
            /* Get next packet data */
            for (c = 0; c < buffer->colors; c++) {
                for (k = 0; k < buffer->packet_size_bytes; k++) {
                    packet[k] = *p_packet++;
                    /* DBG(DBG_info,"buffer_put_full_color_line(): packet[%d] = %02x\n",k,packet[k]); */
                }
                /* Unpack packing_density samples from packet. Of course,
                 * buffer->depth * packing_density <= # bits in packet.
                 * That is checked at buffer creation. */
                for (k = 0; k < buffer->packing_density; k++) {
                    /* Take 1st depth bits and store in val */
                    val = (packet[0] & mask) >> (8-buffer->depth);
                    /* DBG(DBG_info,"buffer_put_full_color_line(): val[%d] = %02x\n",k,val); */
                    /* Now shift packet bytes depth bits left */
                    for (m = 0; m < buffer->packet_size_bytes; m++) {
                        /* Shift left one sample */
                        packet[m] <<= buffer->depth;
                        /* DBG(DBG_info,"buffer_put_full_color_line(): shift packet[%d] = %02x\n",m,packet[m]); */
                        if (m < buffer->packet_size_bytes-1) {
                            /* If there are more bytes, insert 1st depth bits of next byte */
                            packet[m] |= (packet[m+1] >> (8-buffer->depth));
                            /* DBG(DBG_info,"buffer_put_full_color_line(): shift packet[%d] = %02x\n",m,packet[m]); */
                        }
                    }
                    /* Store in buffer */
                    *buffer->p_write[c]++ = val;
                }
                n += buffer->packet_size_bytes;
            }
        }
    }

    /* Update state & statistics */
    buffer->bytes_written += size;
    buffer->bytes_unread += size;

    /* Output current buffer state */
    /* buffer_output_state(buffer); */

    return 1;
}

/**
 * Return bytes from the buffer. Do not mind pixel boundaries.
 * Since the image data is organized in color planes, return bytes from the
 * planes in the defined order. Take care to return multi-byte values after
 * each other. Pack unpacked values.
 *
 * @param buffer Buffer to return bytes from.
 * @param data Byte array to return bytes in
 * @param max_len Maximum number of bytes returned
 * @param len Actual number of bytes returned
 */
void
sanei_pieusb_buffer_get(struct Pieusb_Read_Buffer* buffer, SANE_Byte* data, SANE_Int max_len, SANE_Int* len)
{
    SANE_Byte *pdata;
    SANE_Int n, i, n_bits, N;

    DBG(DBG_info_buffer, "sanei_pieusb_buffer_get() entered\n");

    /* Read from the p_read locations */
    pdata = data;
    n = 0;
    N = buffer->width * buffer->height;
    /* Determine bytes to return */
    if (buffer->packet_size_bytes == 1 && buffer->packing_density == 1) {
        /* Single byte values in buffer */
        while (n < max_len && buffer->bytes_read < buffer->image_size_bytes) {
            /* Return byte*/
            *pdata++ = *(buffer->data + N*buffer->read_index[0] + buffer->width*buffer->read_index[1] + buffer->read_index[2]) & 0xFF;
            /* Update read indices */
            buffer_update_read_index(buffer,1);
            /* Update number of bytes read */
            buffer->bytes_read++;
            n++;
        }
    } else if (buffer->packet_size_bytes == 1 && buffer->packing_density == 8) {
        /* Unpacked bits in buffer: repack */
        while (n < max_len && buffer->bytes_read < buffer->image_size_bytes) {
            uint8_t val = 0;
            /* How many bits to pack? At the end of a line it may be less than 8 */
            n_bits = 8;
            if (buffer->width - buffer->read_index[2] < 8) {
                n_bits = buffer->width - buffer->read_index[2];
            }
            /* Pack n_bits samples from same color plane */
            for (i = 0; i < n_bits; i++) {
                if (*(buffer->data + N*buffer->read_index[0] + buffer->width*buffer->read_index[1] + buffer->read_index[2] + i) > 0) {
                    val |= (0x80 >> i);
                }
            }
            /* Return byte */
            *pdata++ = val;
            /* Update read indices */
            buffer_update_read_index(buffer,n_bits);
            /* Update number of bytes read */
            buffer->bytes_read++;
            n++;
        }
    } else if (buffer->packet_size_bytes == 2) {
        /* Two-byte values in buffer */
        while (n < max_len && buffer->bytes_read < buffer->image_size_bytes) {
            /* Pointer to byte to return */
            SANE_Uint val = *(buffer->data + N*buffer->read_index[0] + buffer->width*buffer->read_index[1] + buffer->read_index[2]);
            /* Return byte */
            if (buffer->read_index[3] == 0) {
                *pdata++ = *((SANE_Byte*)(&val));
            } else {
                *pdata++ = *((SANE_Byte*)(&val)+1);
            }
            /* Update read indices */
            buffer_update_read_index(buffer,1);
            /* Update number of bytes read */
            buffer->bytes_read++;
            n++;
        }
    } else {
        /* not implemented */
        DBG(DBG_error, "buffer_put(): paccket size & density of %d/%d not implemented\n", buffer->packet_size_bytes, buffer->packing_density);
        return;
    }
    *len = n;

    /* Update statistics */
    buffer->bytes_unread -= n;

    /* Output current buffer state */
    /* buffer_output_state(buffer); */
}

/**
 * Update read index to point a given number of bytes past the current position.
 *
 * @param buffer the buffer to initialize
 * @param increment the amount of bytes to move the index
 */
static void buffer_update_read_index(struct Pieusb_Read_Buffer* buffer, int increment)
{
    /* Update read indices
     * [3] = byte-index in 2-byte value: increased first, if we have 2-byte data
     * [2] = index of pixel on line: increased after color plane
     * [1] = index of line: increased after line is complete
     * [0] = color index: increased first since SANE requires full color pixels */
    if (buffer->read_index[3] == 0 && buffer->packet_size_bytes == 2) {
        buffer->read_index[3] = 1;
    } else {
        buffer->read_index[3] = 0;
        buffer->read_index[0]++;
        if (buffer->read_index[0] == buffer->colors) {
            buffer->read_index[0] = 0;
            buffer->read_index[2] += increment;
            if (buffer->read_index[2] >= buffer->width) {
                buffer->read_index[2] = 0;
                buffer->read_index[1]++;
            }
        }
    }
}

#if 0
/**
 * Display the buffer state.
 *
 * @param buffer the buffer to initialize
 */

static void buffer_output_state(struct Pieusb_Read_Buffer* buffer)
{
    SANE_Int line_size;
    SANE_Int N, k, loc[4];

    line_size = buffer->line_size_bytes * buffer->colors; /* Full line size in bytes */

    DBG(DBG_info_buffer, "Buffer data\n");
    DBG(DBG_info_buffer,"  width/height/colors/depth = %d %d %d %d (buffer size %d)\n",
        buffer->width, buffer->height, buffer->colors, buffer->depth, buffer->image_size_bytes);

    /* Summary */
    N = buffer->width * buffer->height;
    for (k = 0; k < buffer->colors; k++) {
        loc[k] = buffer->p_read[k] - buffer->data - k*N;
    }
    for (k = buffer->colors; k < 4; k++) {
        loc[k] = 0;
    }
    DBG(DBG_info_buffer, "  reading at: lines = %d:%d:%d:%d\n", loc[0], loc[1], loc[2], loc[3]);
    for (k = 0; k < buffer->colors; k++) {
        loc[k] = buffer->p_write[k] - buffer->data - k*N;
    }
    for (k = buffer->colors; k < 4; k++) {
        loc[k] = 0;
    }
    DBG(DBG_info_buffer, "  writing at: lines = %d:%d:%d:%d\n", loc[0], loc[1], loc[2], loc[3]);

    /* Progress */
    double fdata = (double)buffer->bytes_unread/buffer->image_size_bytes*100;
    double fread = (double)buffer->bytes_read/buffer->image_size_bytes*100;
    double fwritten = (double)buffer->bytes_written/buffer->image_size_bytes*100;
    DBG(DBG_info_buffer, "  byte counts: image = %d, data = %d (%.0f%%), read = %d (%.0f%%), written = %d (%.0f%%)\n",
        buffer->image_size_bytes, buffer->bytes_unread, fdata, buffer->bytes_read, fread, buffer->bytes_written, fwritten);
    DBG(DBG_info_buffer, "  line counts: image = %.1f, data = %.1f, read = %.1f, written = %.1f\n",
        (double)buffer->image_size_bytes/line_size, (double)buffer->bytes_unread/line_size, (double)buffer->bytes_read/line_size, (double)buffer->bytes_written/line_size);

}
#endif