361 lines
8.1 KiB
C
361 lines
8.1 KiB
C
/* convert_1r.c - Reverse conversion from UTF-8 to extended ASCII. */
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#include "convert/convert.h"
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#include "lib/defs.h"
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enum {
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/* Maximum length of encoded character. */
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kMaxEncodedLength = 8,
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/* Initial number of nodes to allocate when building the tree. */
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kInitialTableAlloc = 8
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};
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struct TEntry {
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/* The output character, or zero if no output. */
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UInt8 output;
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/* The next node, or zero if no next node. */
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UInt8 next;
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};
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/* A node for building the converter. */
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struct TNode {
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struct TEntry entries[256];
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};
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struct TTree {
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struct TNode **nodes;
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int count;
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};
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static ErrorCode CreateTree(struct TTree *tree, Handle data, Size datasz)
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{
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struct TNode **nodes, *node;
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int i, j, dpos, enclen, encend, state, cur, nodecount, nodealloc;
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unsigned ch;
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/* Create a tree with a root node mapping all the ASCII characters except
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NUL, CR, and LF. NUL won't map because an output of 0 is interpreted as
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no output. CR and LF are removed so they can be handled specially be the
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decoder. */
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nodes =
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(struct TNode **)NewHandle(kInitialTableAlloc * sizeof(struct TNode));
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if (nodes == NULL) {
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return kErrorNoMemory;
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}
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nodecount = 1;
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nodealloc = kInitialTableAlloc;
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node = *nodes;
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MemClear(node, sizeof(struct TNode));
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for (i = 0; i < 128; i++) {
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node->entries[i].output = i;
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}
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node->entries[kCharLF].output = 0;
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node->entries[kCharCR].output = 0;
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/* Parse the table data and build up a tree of TNode. */
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dpos = 1;
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/* For each high character (128..255). */
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for (i = 0; i < 128; i++) {
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/* For each encoding of that character. */
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for (j = 0; j < 2; j++) {
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if (dpos >= datasz) {
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goto bad_table;
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}
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enclen = (UInt8)(*data)[dpos++];
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if (enclen != 0) {
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if (enclen < 2 || enclen > datasz - dpos ||
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enclen > kMaxEncodedLength) {
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goto bad_table;
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}
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/* Iterate over all but last byte in encoding, to find the node
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which will produce the decoded byte as output. */
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state = 0;
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node = *nodes;
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for (encend = dpos + enclen - 1; dpos < encend; dpos++) {
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ch = (UInt8)(*data)[dpos];
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cur = state;
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state = node->entries[ch].next;
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if (state == 0) {
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if (nodecount >= nodealloc) {
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nodealloc *= 2;
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if (!ResizeHandle(
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(Handle)nodes,
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nodealloc * sizeof(struct TNode))) {
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DisposeHandle((Handle)nodes);
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return kErrorNoMemory;
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}
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node = *nodes + cur;
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}
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state = nodecount++;
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node->entries[ch].next = state;
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node = (*nodes) + state;
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MemClear(node, sizeof(*node));
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} else {
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node = *nodes + state;
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}
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}
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ch = (UInt8)(*data)[dpos++];
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if (node->entries[ch].output != 0) {
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goto bad_table;
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}
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node->entries[ch].output = i | 0x80;
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}
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}
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}
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if (!ResizeHandle((Handle)nodes, nodecount * sizeof(struct TNode))) {
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DisposeHandle((Handle)nodes);
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return kErrorNoMemory;
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}
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tree->nodes = nodes;
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tree->count = nodecount;
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return 0;
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bad_table:
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DisposeHandle((Handle)nodes);
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return kErrorBadData;
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}
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struct NodeInfo {
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UInt8 min;
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UInt8 max;
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UInt16 offset;
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};
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struct CEntry {
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UInt16 output;
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UInt16 next;
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};
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/* A compressed table node. Followed by an array of centry. */
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struct CNode {
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/* First byte in table. */
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UInt8 base;
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/* Number of entries in table, minus one. */
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UInt8 span;
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};
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static ErrorCode CompactTree(Handle *out, struct TNode **nodes, int nodecount)
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{
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Handle ctree;
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struct TNode *node;
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struct NodeInfo **infos, *info;
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struct CNode *cnode;
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struct CEntry *centry;
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int i, j, min, max, count, next;
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unsigned offset;
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/* Figure out where each compacted node will go. */
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infos = (struct NodeInfo **)NewHandle(sizeof(struct NodeInfo) * nodecount);
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if (infos == NULL) {
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return kErrorNoMemory;
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}
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offset = 0;
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for (i = 0; i < nodecount; i++) {
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node = *nodes + i;
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min = 0;
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while (node->entries[min].output == 0 && node->entries[min].next == 0) {
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min++;
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}
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max = 255;
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while (node->entries[max].output == 0 && node->entries[max].next == 0) {
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max--;
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}
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info = *infos + i;
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info->min = min;
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info->max = max;
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info->offset = offset;
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count = max - min + 1;
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offset += sizeof(struct CNode) + count * sizeof(struct CEntry);
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}
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/* Create the compacted tree. */
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ctree = NewHandle(offset);
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if (ctree == NULL) {
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DisposeHandle((Handle)infos);
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return kErrorNoMemory;
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}
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for (i = 0; i < nodecount; i++) {
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node = *nodes + i;
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info = *infos + i;
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min = info->min;
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max = info->max;
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offset = info->offset;
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cnode = (void *)(*ctree + offset);
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cnode->base = min;
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cnode->span = max - min;
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centry = (void *)(*ctree + offset + sizeof(struct CNode));
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for (j = min; j <= max; j++) {
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centry->output = node->entries[j].output;
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next = node->entries[j].next;
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if (next != 0) {
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next = (*infos)[next].offset;
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}
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centry->next = next;
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centry++;
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}
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}
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DisposeHandle((Handle)infos);
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*out = ctree;
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return 0;
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}
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ErrorCode Convert1rBuild(Handle *out, Handle data, Size datasz)
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{
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struct TTree table;
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ErrorCode err;
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err = CreateTree(&table, data, datasz);
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if (err != 0) {
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return err;
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}
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err = CompactTree(out, table.nodes, table.count);
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DisposeHandle((Handle)table.nodes);
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return err;
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}
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struct Convert1rState {
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UInt8 lastch;
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UInt8 output;
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UInt16 tableoffset;
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};
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void Convert1rRun(const void *cvtptr, LineBreakConversion lc,
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struct ConverterState *stateptr, UInt8 **optr, UInt8 *oend,
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const UInt8 **iptr, const UInt8 *iend)
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{
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struct Convert1rState *state = (struct Convert1rState *)stateptr;
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const struct CNode *node;
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const struct CEntry *entry;
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UInt8 *opos = *optr;
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const UInt8 *ipos = *iptr, *savein;
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unsigned ch, lastch, chlen, output, saveout, toffset, savetoffset;
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ch = state->lastch;
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savein = ipos;
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saveout = state->output;
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toffset = state->tableoffset;
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savetoffset = toffset;
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if (oend - opos < 2) {
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goto done;
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}
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goto resume;
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next_out:
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if (oend - opos < 2) {
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goto done;
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}
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/* Follow state machine to the end. */
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savein = ipos;
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saveout = 0;
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toffset = 0;
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savetoffset = 0;
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resume:
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for (;;) {
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if (ipos >= iend) {
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goto done;
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}
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lastch = ch;
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ch = *ipos++;
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node = (const void *)((const UInt8 *)cvtptr + toffset);
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ch -= node->base;
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if (ch > node->span) {
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toffset = 0;
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goto bad_char;
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}
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entry =
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(const void *)((const UInt8 *)cvtptr + toffset +
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sizeof(struct CNode) + ch * sizeof(struct CEntry));
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output = entry->output;
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toffset = entry->next;
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if (toffset == 0) {
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/* Reached end of tree. */
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if (output == 0) {
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goto bad_char;
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}
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*opos++ = output;
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goto next_out;
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}
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if (output != 0) {
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/* Can produce output here, or can consume more input. We try
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consuming more input, but save the state to rewind if that
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fails. */
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savein = ipos;
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saveout = output;
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savetoffset = toffset;
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}
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}
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bad_char:
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/* Bad character. Back up and try again. */
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ipos = savein;
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if (saveout != 0) {
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/* Produce saved output. */
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*opos++ = saveout;
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ch = 0;
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} else {
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/* No saved output, this really is a bad character. Consume one
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UTF-8 character, emit it as a fallback, and continue. */
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ch = *ipos++;
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if ((ch & 0x80) == 0) {
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/* ASCII character: either NUL, CR, or LF, because only
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these
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characters will result in a transition to state 0. */
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if (ch == 0) {
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*opos++ = ch;
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} else if (ch == kCharLF && lastch == kCharCR) {
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if (lc == kLineBreakKeep) {
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*opos++ = ch;
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}
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} else {
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switch (lc) {
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case kLineBreakKeep:
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*opos++ = ch;
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break;
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case kLineBreakLF:
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*opos++ = kCharLF;
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break;
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case kLineBreakCR:
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*opos++ = kCharCR;
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break;
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case kLineBreakCRLF:
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*opos++ = kCharCR;
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*opos++ = kCharLF;
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break;
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}
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}
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} else {
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if ((ch & 0xe0) == 0xc0) {
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chlen = 1;
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} else if ((ch & 0xf0) == 0xe0) {
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chlen = 2;
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} else if ((ch & 0xf8) == 0xf0) {
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chlen = 3;
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} else {
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chlen = 0;
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}
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for (; chlen > 0; chlen--) {
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if (ipos == iend) {
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goto done;
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}
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ch = *ipos;
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if ((ch & 0xc0) != 0x80) {
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break;
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}
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ipos++;
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}
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*opos++ = kCharSubstitute;
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}
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}
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goto next_out;
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done:
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state->lastch = ch;
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state->output = saveout;
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state->tableoffset = savetoffset;
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*optr = opos;
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*iptr = savein;
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}
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