summaryrefslogtreecommitdiffstats
path: root/media/libjpeg/jchuff.h
diff options
context:
space:
mode:
Diffstat (limited to 'media/libjpeg/jchuff.h')
-rw-r--r--media/libjpeg/jchuff.h50
1 files changed, 50 insertions, 0 deletions
diff --git a/media/libjpeg/jchuff.h b/media/libjpeg/jchuff.h
new file mode 100644
index 0000000000..da7809a94b
--- /dev/null
+++ b/media/libjpeg/jchuff.h
@@ -0,0 +1,50 @@
+/*
+ * jchuff.h
+ *
+ * This file was part of the Independent JPEG Group's software:
+ * Copyright (C) 1991-1997, Thomas G. Lane.
+ * libjpeg-turbo Modifications:
+ * Copyright (C) 2022, D. R. Commander.
+ * For conditions of distribution and use, see the accompanying README.ijg
+ * file.
+ *
+ * This file contains declarations for Huffman entropy encoding routines
+ * that are shared between the sequential encoder (jchuff.c) and the
+ * progressive encoder (jcphuff.c). No other modules need to see these.
+ */
+
+/* The legal range of a DCT coefficient is
+ * -1024 .. +1023 for 8-bit data;
+ * -16384 .. +16383 for 12-bit data.
+ * Hence the magnitude should always fit in 10 or 14 bits respectively.
+ */
+
+#if BITS_IN_JSAMPLE == 8
+#define MAX_COEF_BITS 10
+#else
+#define MAX_COEF_BITS 14
+#endif
+
+/* The progressive Huffman encoder uses an unsigned 16-bit data type to store
+ * absolute values of coefficients, because it is possible to inject a
+ * coefficient value of -32768 into the encoder by attempting to transform a
+ * malformed 12-bit JPEG image, and the absolute value of -32768 would overflow
+ * a signed 16-bit integer.
+ */
+typedef unsigned short UJCOEF;
+
+/* Derived data constructed for each Huffman table */
+
+typedef struct {
+ unsigned int ehufco[256]; /* code for each symbol */
+ char ehufsi[256]; /* length of code for each symbol */
+ /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */
+} c_derived_tbl;
+
+/* Expand a Huffman table definition into the derived format */
+EXTERN(void) jpeg_make_c_derived_tbl(j_compress_ptr cinfo, boolean isDC,
+ int tblno, c_derived_tbl **pdtbl);
+
+/* Generate an optimal table definition given the specified counts */
+EXTERN(void) jpeg_gen_optimal_table(j_compress_ptr cinfo, JHUFF_TBL *htbl,
+ long freq[]);