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求各位帮忙看看这个代码,帮我详细解说下这串代码怎么看

请各位给个稍微详细点的解说吧,谢谢

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Templar_M
发帖于7年前 13回/703阅
共有13个答案 最后回答: 7年前

/*
 * qrencode - QR Code encoder
 *
 * Copyright (C) 2006-2010 Kentaro Fukuchi <fukuchi@megaui.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "config.h"
#include "qrencode.h"
#include "qrspec.h"
#include "bitstream.h"
#include "qrinput.h"
#include "rscode.h"
#include "split.h"
#include "mask.h"

/******************************************************************************
 * Raw code
 *****************************************************************************/

typedef struct {
 int dataLength;
 unsigned char *data;
 int eccLength;
 unsigned char *ecc;
} RSblock;

typedef struct {
 int version;
 unsigned char *datacode;
 unsigned char *ecccode;
 int blocks;
 RSblock *rsblock;
 int count;
 int dataLength;
 int eccLength;
 int b1;
} QRRawCode;

static void RSblock_initBlock(RSblock *block, int dl, unsigned char *data, int el, unsigned char *ecc, RS *rs)
{
 block->dataLength = dl;
 block->data = data;
 block->eccLength = el;
 block->ecc = ecc;

 encode_rs_char(rs, data, ecc);
}

static int RSblock_init(RSblock *blocks, int spec[5], unsigned char *data, unsigned char *ecc)
{
 int i;
 RSblock *block;
 unsigned char *dp, *ep;
 RS *rs;
 int el, dl;

 dl = QRspec_rsDataCodes1(spec);
 el = QRspec_rsEccCodes1(spec);
 rs = init_rs(8, 0x11d, 0, 1, el, 255 - dl - el);
 if(rs == NULL) return -1;

 block = blocks;
 dp = data;
 ep = ecc;
 for(i=0; i<QRspec_rsBlockNum1(spec); i++) {
  RSblock_initBlock(block, dl, dp, el, ep, rs);
  dp += dl;
  ep += el;
  block++;
 }

 if(QRspec_rsBlockNum2(spec) == 0) return 0;

 dl = QRspec_rsDataCodes2(spec);
 el = QRspec_rsEccCodes2(spec);
 rs = init_rs(8, 0x11d, 0, 1, el, 255 - dl - el);
 if(rs == NULL) return -1;
 for(i=0; i<QRspec_rsBlockNum2(spec); i++) {
  RSblock_initBlock(block, dl, dp, el, ep, rs);
  dp += dl;
  ep += el;
  block++;
 }

 return 0;
}

__STATIC void QRraw_free(QRRawCode *raw);
__STATIC QRRawCode *QRraw_new(QRinput *input)
{
 QRRawCode *raw;
 int spec[5], ret;

 raw = (QRRawCode *)malloc(sizeof(QRRawCode));
 if(raw == NULL) return NULL;

 raw->datacode = QRinput_getByteStream(input);
 if(raw->datacode == NULL) {
  free(raw);
  return NULL;
 }

 QRspec_getEccSpec(input->version, input->level, spec);

 raw->version = input->version;
 raw->b1 = QRspec_rsBlockNum1(spec);
 raw->dataLength = QRspec_rsDataLength(spec);
 raw->eccLength = QRspec_rsEccLength(spec);
 raw->ecccode = (unsigned char *)malloc(raw->eccLength);
 if(raw->ecccode == NULL) {
  free(raw->datacode);
  free(raw);
  return NULL;
 }

 raw->blocks = QRspec_rsBlockNum(spec);
 raw->rsblock = (RSblock *)calloc(sizeof(RSblock), raw->blocks);
 if(raw->rsblock == NULL) {
  QRraw_free(raw);
  return NULL;
 }
 ret = RSblock_init(raw->rsblock, spec, raw->datacode, raw->ecccode);
 if(ret < 0) {
  QRraw_free(raw);
  return NULL;
 }

 raw->count = 0;

 return raw;
}

/**
 * Return a code (byte).
 * This function can be called iteratively.
 * @param raw raw code.
 * @return code
 */
__STATIC unsigned char QRraw_getCode(QRRawCode *raw)
{
 int col, row;
 unsigned char ret;

 if(raw->count < raw->dataLength) {
  row = raw->count % raw->blocks;
  col = raw->count / raw->blocks;
  if(col >= raw->rsblock[0].dataLength) {
   row += raw->b1;
  }
  ret = raw->rsblock[row].data[col];
 } else if(raw->count < raw->dataLength + raw->eccLength) {
  row = (raw->count - raw->dataLength) % raw->blocks;
  col = (raw->count - raw->dataLength) / raw->blocks;
  ret = raw->rsblock[row].ecc[col];
 } else {
  return 0;
 }
 raw->count++;
 return ret;
}

__STATIC void QRraw_free(QRRawCode *raw)
{
 if(raw != NULL) {
  free(raw->datacode);
  free(raw->ecccode);
  if(raw->rsblock != NULL) {
   free(raw->rsblock);
  }
  free(raw);
 }
}

/******************************************************************************
 * Frame filling
 *****************************************************************************/

typedef struct {
 int width;
 unsigned char *frame;
 int x, y;
 int dir;
 int bit;
} FrameFiller;

static FrameFiller *FrameFiller_new(int width, unsigned char *frame)
{
 FrameFiller *filler;

 filler = (FrameFiller *)malloc(sizeof(FrameFiller));
 if(filler == NULL) return NULL;
 filler->width = width;
 filler->frame = frame;
 filler->x = width - 1;
 filler->y = width - 1;
 filler->dir = -1;
 filler->bit = -1;

 return filler;
}

static unsigned char *FrameFiller_next(FrameFiller *filler)
{
 unsigned char *p;
 int x, y, w;

 if(filler->bit == -1) {
  filler->bit = 0;
  return filler->frame + filler->y * filler->width + filler->x;
 }

 x = filler->x;
 y = filler->y;
 p = filler->frame;
 w = filler->width;

 if(filler->bit == 0) {
  x--;
  filler->bit++;
 } else {
  x++;
  y += filler->dir;
  filler->bit--;
 }

 if(filler->dir < 0) {
  if(y < 0) {
   y = 0;
   x -= 2;
   filler->dir = 1;
   if(x == 6) {
    x--;
    y = 9;
   }
  }
 } else {
  if(y == w) {
   y = w - 1;
   x -= 2;
   filler->dir = -1;
   if(x == 6) {
    x--;
    y -= 8;
   }
  }
 }
 if(x < 0 || y < 0) return NULL;

 filler->x = x;
 filler->y = y;

 if(p[y * w + x] & 0x80) {
  // This tail recursion could be optimized.
  return FrameFiller_next(filler);
 }
 return &p[y * w + x];
}

#if 0
unsigned char *FrameFiller_fillerTest(int version)
{
 int width, length;
 unsigned char *frame, *p;
 FrameFiller *filler;
 int i, j;
 unsigned char cl = 1;
 unsigned char ch = 0;

 width = QRspec_getWidth(version);
 frame = QRspec_newFrame(version);
 filler = FrameFiller_new(width, frame);
 length = QRspec_getDataLength(version, QR_ECLEVEL_L)
   + QRspec_getECCLength(version, QR_ECLEVEL_L);

 for(i=0; i<length; i++) {
  for(j=0; j<8; j++) {
   p = FrameFiller_next(filler);
   *p = ch | cl;
   cl++;
   if(cl == 9) {
    cl = 1;
    ch += 0x10;
   }
  }
 }
 length = QRspec_getRemainder(version);
 for(i=0; i<length; i++) {
  p = FrameFiller_next(filler);
  *p = 0xa0;
 }
 p = FrameFiller_next(filler);
 free(filler);
 if(p != NULL) {
  return NULL;
 }

 return frame;
}
#endif


/******************************************************************************
 * QR-code encoding
 *****************************************************************************/

static QRcode *QRcode_new(int version, int width, unsigned char *data)
{
 QRcode *qrcode;

 qrcode = (QRcode *)malloc(sizeof(QRcode));
 if(qrcode == NULL) return NULL;

 qrcode->version = version;
 qrcode->width = width;
 qrcode->data = data;

 return qrcode;
}

void QRcode_free(QRcode *qrcode)
{
 if(qrcode != NULL) {
  free(qrcode->data);
  free(qrcode);
 }
}

__STATIC QRcode *QRcode_encodeMask(QRinput *input, int mask)
{
 int width, version;
 QRRawCode *raw;
 unsigned char *frame, *masked, *p, code, bit;
 FrameFiller *filler;
 int i, j;
 QRcode *qrcode;

 if(input->version < 0 || input->version > QRSPEC_VERSION_MAX) {
  errno = EINVAL;
  return NULL;
 }
 if(input->level > QR_ECLEVEL_H) {
  errno = EINVAL;
  return NULL;
 }

 raw = QRraw_new(input);
 if(raw == NULL) return NULL;

 version = raw->version;
 width = QRspec_getWidth(version);
 frame = QRspec_newFrame(version);
 if(frame == NULL) {
  QRraw_free(raw);
  return NULL;
 }
 filler = FrameFiller_new(width, frame);
 if(filler == NULL) {
  QRraw_free(raw);
  free(frame);
  return NULL;
 }

 /* inteleaved data and ecc codes */
 for(i=0; i<raw->dataLength + raw->eccLength; i++) {
  code = QRraw_getCode(raw);
  bit = 0x80;
  for(j=0; j<8; j++) {
   p = FrameFiller_next(filler);
   *p = 0x02 | ((bit & code) != 0);
   bit = bit >> 1;
  }
 }
 QRraw_free(raw);
 /* remainder bits */
 j = QRspec_getRemainder(version);
 for(i=0; i<j; i++) {
  p = FrameFiller_next(filler);
  *p = 0x02;
 }
 free(filler);
 /* masking */
 if(mask < 0) {
  masked = Mask_mask(width, frame, input->level);
 } else {
  masked = Mask_makeMask(width, frame, mask, input->level);
 }
 if(masked == NULL) {
  free(frame);
  return NULL;
 }
 qrcode = QRcode_new(version, width, masked);

 free(frame);

 return qrcode;
}

QRcode *QRcode_encodeInput(QRinput *input)
{
 return QRcode_encodeMask(input, -1);
}

QRcode *QRcode_encodeString8bit(const char *string, int version, QRecLevel level)
{
 QRinput *input;
 QRcode *code;
 int ret;

 if(string == NULL) {
  errno = EINVAL;
  return NULL;
 }

 input = QRinput_new2(version, level);
 if(input == NULL) return NULL;

 ret = QRinput_append(input, QR_MODE_8, strlen(string), (unsigned char *)string);
 if(ret < 0) {
  QRinput_free(input);
  return NULL;
 }
 code = QRcode_encodeInput(input);
 QRinput_free(input);

 return code;
}

QRcode *QRcode_encodeString(const char *string, int version, QRecLevel level, QRencodeMode hint, int casesensitive)
{
 QRinput *input;
 QRcode *code;
 int ret;

 if(hint != QR_MODE_8 && hint != QR_MODE_KANJI) {
  errno = EINVAL;
  return NULL;
 }

 input = QRinput_new2(version, level);
 if(input == NULL) return NULL;

 ret = Split_splitStringToQRinput(string, input, hint, casesensitive);
 if(ret < 0) {
  QRinput_free(input);
  return NULL;
 }

 code = QRcode_encodeInput(input);
 QRinput_free(input);

 return code;
}

/******************************************************************************
 * Structured QR-code encoding
 *****************************************************************************/

static QRcode_List *QRcode_List_newEntry(void)
{
 QRcode_List *entry;

 entry = (QRcode_List *)malloc(sizeof(QRcode_List));
 if(entry == NULL) return NULL;

 entry->next = NULL;
 entry->code = NULL;

 return entry;
}

static void QRcode_List_freeEntry(QRcode_List *entry)
{
 if(entry != NULL) {
  QRcode_free(entry->code);
  free(entry);
 }
}

void QRcode_List_free(QRcode_List *qrlist)
{
 QRcode_List *list = qrlist, *next;

 while(list != NULL) {
  next = list->next;
  QRcode_List_freeEntry(list);
  list = next;
 }
}

int QRcode_List_size(QRcode_List *qrlist)
{
 QRcode_List *list = qrlist;
 int size = 0;

 while(list != NULL) {
  size++;
  list = list->next;
 }

 return size;
}

#if 0
static unsigned char QRcode_parity(const char *str, int size)
{
 unsigned char parity = 0;
 int i;

 for(i=0; i<size; i++) {
  parity ^= str[i];
 }

 return parity;
}
#endif

QRcode_List *QRcode_encodeInputStructured(QRinput_Struct *s)
{
 QRcode_List *head = NULL;
 QRcode_List *tail = NULL;
 QRcode_List *entry;
 QRinput_InputList *list = s->head;

 while(list != NULL) {
  if(head == NULL) {
   entry = QRcode_List_newEntry();
   if(entry == NULL) goto ABORT;
   head = entry;
   tail = head;
  } else {
   entry = QRcode_List_newEntry();
   if(entry == NULL) goto ABORT;
   tail->next = entry;
   tail = tail->next;
  }
  tail->code = QRcode_encodeInput(list->input);
  if(tail->code == NULL) {
   goto ABORT;
  }
  list = list->next;
 }

 return head;
ABORT:
 QRcode_List_free(head);
 return NULL;
}

static QRcode_List *QRcode_encodeInputToStructured(QRinput *input)
{
 QRinput_Struct *s;
 QRcode_List *codes;

 s = QRinput_splitQRinputToStruct(input);
 if(s == NULL) return NULL;

 codes = QRcode_encodeInputStructured(s);
 QRinput_Struct_free(s);

 return codes;
}

QRcode_List *QRcode_encodeString8bitStructured(const char *string, int version, QRecLevel level)
{
 QRinput *input;
 QRcode_List *codes;
 int ret;

 if(version <= 0) {
  errno = EINVAL;
  return NULL;
 }

 input = QRinput_new2(version, level);
 if(input == NULL) return NULL;

 ret = QRinput_append(input, QR_MODE_8, strlen(string), (unsigned char *)string);
 if(ret < 0) {
  QRinput_free(input);
  return NULL;
 }
 codes = QRcode_encodeInputToStructured(input);
 QRinput_free(input);

 return codes;
}

QRcode_List *QRcode_encodeStringStructured(const char *string, int version, QRecLevel level, QRencodeMode hint, int casesensitive)
{
 QRinput *input;
 QRcode_List *codes;
 int ret;

 if(version <= 0) {
  errno = EINVAL;
  return NULL;
 }
 if(hint != QR_MODE_8 && hint != QR_MODE_KANJI) {
  errno = EINVAL;
  return NULL;
 }

 input = QRinput_new2(version, level);
 if(input == NULL) return NULL;

 ret = Split_splitStringToQRinput(string, input, hint, casesensitive);
 if(ret < 0) {
  QRinput_free(input);
  return NULL;
 }
 codes = QRcode_encodeInputToStructured(input);
 QRinput_free(input);

 return codes;
}

有许多函数定义在其他头文件,你只给一段代码(或是一个c文件的代码),你指望大家能告诉你什么?

似乎是计算二维条形码的东东?这种东西你要先搞清是如何得到二维条形码(二维条形码算法),再看程序就容易看懂了,光看程序不太容易看懂。

引用来自#8楼“six”的帖子

有许多函数定义在其他头文件,你只给一段代码(或是一个c文件的代码),你指望大家能告诉你什么?

 能留你邮箱否,我发你下,这上面我的代码包传不上来

9楼说得对,你先要知道你的代码实现的是什么,然后顺着算法看下去,代码就容易懂了,但是前提是你的 C语言 基础得好。

你的代码量估计挺大,要我看懂再告诉你,估计那时你自己都看得懂了

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