The Independent JPEG Group's JPEG software v5
diff --git a/wrppm.c b/wrppm.c
new file mode 100644
index 0000000..4f7a2cb
--- /dev/null
+++ b/wrppm.c
@@ -0,0 +1,248 @@
+/*
+ * wrppm.c
+ *
+ * Copyright (C) 1991-1994, Thomas G. Lane.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains routines to write output images in PPM/PGM format.
+ * The PBMPLUS library is NOT required to compile this software
+ * (but it is highly useful as a set of PPM image manipulation programs).
+ *
+ * These routines may need modification for non-Unix environments or
+ * specialized applications. As they stand, they assume output to
+ * an ordinary stdio stream.
+ */
+
+#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */
+
+#ifdef PPM_SUPPORTED
+
+
+/*
+ * Currently, this code only knows how to write raw PPM or PGM format,
+ * which can be no more than 8 bits/sample. As an expedient for testing
+ * 12-bit JPEG mode, we support writing 12-bit data to an 8-bit file by
+ * downscaling the values. Of course this implies loss of precision.
+ * (When the core library supports data precision reduction, a cleaner
+ * implementation will be to ask for that instead.)
+ */
+
+#if BITS_IN_JSAMPLE == 8
+#define DOWNSCALE(x) (x)
+#else
+#define DOWNSCALE(x) ((x) >> (BITS_IN_JSAMPLE-8))
+#endif
+
+
+/*
+ * When JSAMPLE is the same size as char, we can just fwrite() the
+ * decompressed data to the PPM or PGM file. On PCs, in order to make this
+ * work the output buffer must be allocated in near data space, because we are
+ * assuming small-data memory model wherein fwrite() can't reach far memory.
+ * If you need to process very wide images on a PC, you might have to compile
+ * in large-memory model, or else replace fwrite() with a putc() loop ---
+ * which will be much slower.
+ */
+
+
+/* Private version of data destination object */
+
+typedef struct {
+ struct djpeg_dest_struct pub; /* public fields */
+
+ /* Usually these two pointers point to the same place: */
+ char *iobuffer; /* fwrite's I/O buffer */
+ JSAMPROW pixrow; /* decompressor output buffer */
+
+ JDIMENSION buffer_width; /* width of one row */
+} ppm_dest_struct;
+
+typedef ppm_dest_struct * ppm_dest_ptr;
+
+
+/*
+ * Write some pixel data.
+ * In this module rows_supplied will always be 1.
+ *
+ * put_pixel_rows handles the "normal" 8-bit case where the decompressor
+ * output buffer is physically the same as the fwrite buffer.
+ */
+
+METHODDEF void
+put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
+ JDIMENSION rows_supplied)
+{
+ ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
+
+ (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
+}
+
+
+/*
+ * This code is used when we have to copy the data because JSAMPLE is not
+ * the same size as char. Typically this only happens in 12-bit mode.
+ */
+
+METHODDEF void
+copy_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
+ JDIMENSION rows_supplied)
+{
+ ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
+ register char * bufferptr;
+ register JSAMPROW ptr;
+ register JDIMENSION col;
+
+ ptr = dest->pub.buffer[0];
+ bufferptr = dest->iobuffer;
+ for (col = dest->buffer_width; col > 0; col--) {
+ *bufferptr++ = (char) DOWNSCALE(GETJSAMPLE(*ptr++));
+ }
+ (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
+}
+
+
+/*
+ * Write some pixel data when color quantization is in effect.
+ * We have to demap the color index values to straight data.
+ */
+
+METHODDEF void
+put_demapped_rgb (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
+ JDIMENSION rows_supplied)
+{
+ ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
+ register char * bufferptr;
+ register int pixval;
+ register JSAMPROW ptr;
+ register JSAMPROW color_map0 = cinfo->colormap[0];
+ register JSAMPROW color_map1 = cinfo->colormap[1];
+ register JSAMPROW color_map2 = cinfo->colormap[2];
+ register JDIMENSION col;
+
+ ptr = dest->pub.buffer[0];
+ bufferptr = dest->iobuffer;
+ for (col = cinfo->output_width; col > 0; col--) {
+ pixval = GETJSAMPLE(*ptr++);
+ *bufferptr++ = (char) DOWNSCALE(GETJSAMPLE(color_map0[pixval]));
+ *bufferptr++ = (char) DOWNSCALE(GETJSAMPLE(color_map1[pixval]));
+ *bufferptr++ = (char) DOWNSCALE(GETJSAMPLE(color_map2[pixval]));
+ }
+ (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
+}
+
+
+METHODDEF void
+put_demapped_gray (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
+ JDIMENSION rows_supplied)
+{
+ ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
+ register char * bufferptr;
+ register JSAMPROW ptr;
+ register JSAMPROW color_map = cinfo->colormap[0];
+ register JDIMENSION col;
+
+ ptr = dest->pub.buffer[0];
+ bufferptr = dest->iobuffer;
+ for (col = cinfo->output_width; col > 0; col--) {
+ *bufferptr++ = (char) DOWNSCALE(GETJSAMPLE(color_map[GETJSAMPLE(*ptr++)]));
+ }
+ (void) JFWRITE(dest->pub.output_file, dest->iobuffer, dest->buffer_width);
+}
+
+
+/*
+ * Startup: write the file header.
+ */
+
+METHODDEF void
+start_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
+{
+ ppm_dest_ptr dest = (ppm_dest_ptr) dinfo;
+
+ /* Emit file header */
+ switch (cinfo->out_color_space) {
+ case JCS_GRAYSCALE:
+ /* emit header for raw PGM format */
+ fprintf(dest->pub.output_file, "P5\n%ld %ld\n%d\n",
+ (long) cinfo->output_width, (long) cinfo->output_height, 255);
+ break;
+ case JCS_RGB:
+ /* emit header for raw PPM format */
+ fprintf(dest->pub.output_file, "P6\n%ld %ld\n%d\n",
+ (long) cinfo->output_width, (long) cinfo->output_height, 255);
+ break;
+ default:
+ ERREXIT(cinfo, JERR_PPM_COLORSPACE);
+ }
+}
+
+
+/*
+ * Finish up at the end of the file.
+ */
+
+METHODDEF void
+finish_output_ppm (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
+{
+ /* Make sure we wrote the output file OK */
+ fflush(dinfo->output_file);
+ if (ferror(dinfo->output_file))
+ ERREXIT(cinfo, JERR_FILE_WRITE);
+}
+
+
+/*
+ * The module selection routine for PPM format output.
+ */
+
+GLOBAL djpeg_dest_ptr
+jinit_write_ppm (j_decompress_ptr cinfo)
+{
+ ppm_dest_ptr dest;
+
+ /* Create module interface object, fill in method pointers */
+ dest = (ppm_dest_ptr)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ SIZEOF(ppm_dest_struct));
+ dest->pub.start_output = start_output_ppm;
+ dest->pub.finish_output = finish_output_ppm;
+
+ /* Calculate output image dimensions so we can allocate space */
+ jpeg_calc_output_dimensions(cinfo);
+
+ /* Create physical I/O buffer. Note we make this near on a PC. */
+ dest->buffer_width = cinfo->output_width * cinfo->out_color_components;
+ dest->iobuffer = (char *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (size_t) (dest->buffer_width * SIZEOF(char)));
+
+ if (cinfo->quantize_colors || SIZEOF(JSAMPLE) != SIZEOF(char)) {
+ /* When quantizing, we need an output buffer for colormap indexes
+ * that's separate from the physical I/O buffer. We also need a
+ * separate buffer if JSAMPLE and char are not the same size.
+ */
+ dest->pub.buffer = (*cinfo->mem->alloc_sarray)
+ ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ cinfo->output_width * cinfo->output_components, (JDIMENSION) 1);
+ dest->pub.buffer_height = 1;
+ if (! cinfo->quantize_colors)
+ dest->pub.put_pixel_rows = copy_pixel_rows;
+ else if (cinfo->out_color_space == JCS_GRAYSCALE)
+ dest->pub.put_pixel_rows = put_demapped_gray;
+ else
+ dest->pub.put_pixel_rows = put_demapped_rgb;
+ } else {
+ /* We will fwrite() directly from decompressor output buffer. */
+ /* Synthesize a JSAMPARRAY pointer structure */
+ /* Cast here implies near->far pointer conversion on PCs */
+ dest->pixrow = (JSAMPROW) dest->iobuffer;
+ dest->pub.buffer = & dest->pixrow;
+ dest->pub.buffer_height = 1;
+ dest->pub.put_pixel_rows = put_pixel_rows;
+ }
+
+ return (djpeg_dest_ptr) dest;
+}
+
+#endif /* PPM_SUPPORTED */
