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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /support/dktools/dk4rld.ctr
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+%% options
+
+copyright owner = Dirk Krause
+copyright year = 2015-xxxx
+license = bsd
+
+
+%% header
+
+/** @file dk4rld.h Run-length decoder.
+
+Use dk4rld_init() to initialize the decoder before feeding data to it.
+
+Feed the encoded data into the decoder byte by byte, use the
+dk4rld_add() function.
+If the function returns DK4_EDSTM_ACCEPT, the input was successfully stored
+into the internal data structures, not need for further action.
+If the function returns DK4_EDSTM_FINISHED, an output secquence was
+completed, either a run or a literal byte sequence. Use dk4rld_output()
+to retrieve output data.
+If the dk4rld_add function returns DK4_EDSTM_STOP, an end of data
+(EOD) marker was found; do not feed further bytes into the decoder.
+
+After feeding all input bytes into the decoder, use dk4rld_finish() to check
+syntax. If the function returns DK4_EDSTM_ERROR, the input data stream
+was not properly run-length encoded.
+*/
+
+#include "dk4error.h"
+
+/** Run length decoder.
+*/
+typedef struct {
+ unsigned char ob[128]; /**< Output buffer. */
+ size_t oused; /**< Number of used bytes in ob. */
+ size_t ll; /**< Number of expected bytes. */
+ int st; /**< Current state. */
+} dk4_rl_dec_t;
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Initialize decoder.
+ @param dec Decoder to initialize.
+ @param erp Error report, may be NULL.
+
+ Error codes:
+ - DK4_E_INVALID_ARGUMENTS if enc is NULL.
+*/
+void
+dk4rld_init(dk4_rl_dec_t *dec, dk4_er_t *erp);
+
+/** Add one encoded byte to decoder.
+ @param dec Decoder.
+ @param inbyte Byte to process.
+ @param erp Error report, may be NULL.
+ @return Action to take, one from:
+ - DK4_EDSTM_ACCEPT<br>
+ if the byte was successfully added
+ to the internal data structures, no further action necessary.
+ - DK4_EDSTM_FINISHED<br>
+ if output is available, use dk4rld_output() to retrieve output.
+ - DK4_EDSTM_STOP<br>
+ if an EOD marker was detected. Do not feed further bytes
+ to the decoder.
+ - DK4_EDSTM_ERROR<br>
+ if an error occured.
+
+ Error codes:
+ - DK4_E_INVALID_ARGUMENTS if enc is NULL.
+*/
+int
+dk4rld_add(dk4_rl_dec_t *dec, unsigned char inbyte, dk4_er_t *erp);
+
+/** Finish decoding.
+ @param dec Decoder.
+ @param erp Error report, may be NULL.
+ @return Action to take, one from:
+ - DK4_EDSTM_ACCEPT<br>
+ if no remaining data is stored in the decoder, no further
+ action necessary.
+ - DK4_EDSTM_FINISHED<br>
+ if output is available, use dk4rld_output() to retrieve output.
+ - DK4_EDSTM_ERROR<br>
+ if an error occured.
+
+ Error codes:
+ - DK4_E_INVALID_ARGUMENTS<br>
+ if enc is NULL.
+ - DK4_E_SYNTAX<br>
+ if data indicated by the run-length byte or literally-length
+ byte is missing.
+*/
+int
+dk4rld_finish(dk4_rl_dec_t *dec, dk4_er_t *erp);
+
+/** Retrieve decoder output.
+ @param dptr Address of pointer to set to decoder output,
+ should be initialized to NULL.
+ @param szptr Address of variable to receive buffer size,
+ should be initialized to 0.
+ @param dec Decoder.
+ @param erp Error report, may be NULL.
+ @return 1 if data is available, 0 otherwise.
+
+ Error codes:
+ - DK4_E_INVALID_ARGUMENTS if enc is NULL.
+*/
+int
+dk4rld_output(
+ const unsigned char **dptr, size_t *szptr, dk4_rl_dec_t *dec, dk4_er_t *erp
+);
+
+#ifdef __cplusplus
+}
+#endif
+
+%% module
+
+#include "dk4rld.h"
+#include "dk4edstm.h"
+#include "dk4mem.h"
+
+
+
+$!trace-include
+
+
+
+/** Decoder states.
+*/
+enum {
+ /** Start state, exepect run length
+ or literal data length.
+ */
+ RLD_ST_EXPECT_KEY_BYTE = 0,
+
+ /** Expect byte value for run.
+ */
+ RLD_ST_EXPECT_RUN_BYTE ,
+
+ /** Expect literal byte.
+ */
+ RLD_ST_EXPECT_LITERAL_BYTE ,
+
+ /** No further input accepted as
+ EOD marker was found.
+ */
+ RLD_ST_EOD_FOUND
+};
+
+
+
+void
+dk4rld_init(dk4_rl_dec_t *dec, dk4_er_t *erp)
+{
+ $? "+ dk4rld_init"
+ if (NULL != dec) {
+ DK4_MEMRES(dec, sizeof(dk4_rl_dec_t));
+ dec->oused = 0;
+ dec->ll = 0;
+ dec->st = RLD_ST_EXPECT_KEY_BYTE;
+ } else {
+ dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
+ } $? "- dk4rld_init"
+}
+
+
+
+int
+dk4rld_add(dk4_rl_dec_t *dec, unsigned char inbyte, dk4_er_t *erp)
+{
+ int back = DK4_EDSTM_ERROR;
+ $? "+ dk4rld_add"
+ if (NULL != dec) {
+ switch (dec->st) {
+ case RLD_ST_EXPECT_KEY_BYTE : {
+ if ((unsigned char)128 > inbyte) {
+ /*
+ Literal byte sequence
+ */
+ dec->st = RLD_ST_EXPECT_LITERAL_BYTE;
+ dec->ll = (size_t)inbyte + 1;
+ back = DK4_EDSTM_ACCEPT;
+ } else {
+ if ((unsigned char)128 < inbyte) {
+ /*
+ Run of equal bytes
+ */
+ dec->st = RLD_ST_EXPECT_RUN_BYTE;
+ dec->ll = (size_t)257 - (size_t)inbyte;
+ back = DK4_EDSTM_ACCEPT;
+ } else {
+ /*
+ EOD marker found
+ */
+ dec->st = RLD_ST_EOD_FOUND;
+ back = DK4_EDSTM_STOP;
+ }
+ }
+ } break;
+ case RLD_ST_EXPECT_RUN_BYTE : {
+ dk4mem_set(&(dec->ob[0]), dec->ll, inbyte, NULL);
+ dec->oused = dec->ll;
+ dec->st = RLD_ST_EXPECT_KEY_BYTE;
+ back = DK4_EDSTM_FINISHED;
+ } break;
+ case RLD_ST_EXPECT_LITERAL_BYTE : {
+ dec->ob[0] = inbyte;
+ dec->oused = 1;
+ dec->ll -= 1;
+ if (0 == dec->ll) {
+ dec->st = RLD_ST_EXPECT_KEY_BYTE;
+ }
+ back = DK4_EDSTM_FINISHED;
+ } break;
+ default : {
+ dk4error_set_simple_error_code(erp, DK4_E_SYNTAX);
+ } break;
+ }
+ } else {
+ dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
+ } $? "- dk4rld_add %d", back
+ return back;
+}
+
+
+
+int
+dk4rld_finish(dk4_rl_dec_t *dec, dk4_er_t *erp)
+{
+ int back = DK4_EDSTM_ERROR;
+ $? "+ dk4rld_finish"
+ if (NULL != dec) {
+ switch (dec->st) {
+ case RLD_ST_EXPECT_KEY_BYTE : case RLD_ST_EOD_FOUND : {
+ back = DK4_EDSTM_ACCEPT;
+ } break;
+ default : {
+ dk4error_set_simple_error_code(erp, DK4_E_SYNTAX);
+ } break;
+ }
+ } else {
+ dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
+ } $? "- dk4rld_finish %d", back
+ return back;
+}
+
+
+
+int
+dk4rld_output(
+ const unsigned char **dptr, size_t *szptr, dk4_rl_dec_t *dec, dk4_er_t *erp
+)
+{
+ int back = 0;
+ $? "+ dk4rld_output"
+ if (NULL != dec) {
+ if (0 < dec->oused) {
+ *dptr = &(dec->ob[0]);
+ *szptr = dec->oused;
+ back = 1;
+ } else {
+ *dptr = NULL;
+ *szptr = 0;
+ }
+ } else {
+ dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
+ } $? "- dk4rld_output %d", back
+ return back;
+}
+