Updated rasm to 1.7

1 files changed, 164 insertions, 0 deletions

diff --git a/tools/rasm/ZX0-main/src/compress.c b/tools/rasm/ZX0-main/src/compress.c
new file mode 100644
index 0000000..7feb567
--- /dev/null
+++ b/tools/rasm/ZX0-main/src/compress.c
@@ -0,0 +1,164 @@
+/*
+ * (c) Copyright 2021 by Einar Saukas. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * The name of its author may not be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "zx0.h"
+
+unsigned char* output_data;
+int output_index;
+int input_index;
+int bit_index;
+int bit_mask;
+int diff;
+int backtrack;
+
+void read_bytes(int n, int *delta) {
+    input_index += n;
+    diff += n;
+    if (*delta < diff)
+        *delta = diff;
+}
+
+void write_byte(int value) {
+    output_data[output_index++] = value;
+    diff--;
+}
+
+void write_bit(int value) {
+    if (backtrack) {
+        if (value)
+            output_data[output_index-1] |= 1;
+        backtrack = FALSE;
+    } else {
+        if (!bit_mask) {
+            bit_mask = 128;
+            bit_index = output_index;
+            write_byte(0);
+        }
+        if (value)
+            output_data[bit_index] |= bit_mask;
+        bit_mask >>= 1;
+    }
+}
+
+void write_interlaced_elias_gamma(int value, int backwards_mode, int invert_mode) {
+    int i;
+
+    for (i = 2; i <= value; i <<= 1)
+        ;
+    i >>= 1;
+    while (i >>= 1) {
+        write_bit(backwards_mode);
+        write_bit(invert_mode ? !(value & i) : (value & i));
+    }
+    write_bit(!backwards_mode);
+}
+
+unsigned char *zx0_compress(BLOCK *optimal, unsigned char *input_data, int input_size, int skip, int backwards_mode, int invert_mode, int *output_size, int *delta) {
+    BLOCK *prev;
+    BLOCK *next;
+    int last_offset = INITIAL_OFFSET;
+    int length;
+    int i;
+
+    /* calculate and allocate output buffer */
+    *output_size = (optimal->bits+25)/8;
+    output_data = (unsigned char *)malloc(*output_size);
+    if (!output_data) {
+         fprintf(stderr, "Error: Insufficient memory\n");
+         exit(1);
+    }
+
+    /* un-reverse optimal sequence */
+    prev = NULL;
+    while (optimal) {
+        next = optimal->chain;
+        optimal->chain = prev;
+        prev = optimal;
+        optimal = next;
+    }
+
+    /* initialize data */
+    diff = *output_size-input_size+skip;
+    *delta = 0;
+    input_index = skip;
+    output_index = 0;
+    bit_mask = 0;
+    backtrack = TRUE;
+
+    /* generate output */
+    for (optimal = prev->chain; optimal; prev=optimal, optimal = optimal->chain) {
+        length = optimal->index-prev->index;
+
+        if (!optimal->offset) {
+            /* copy literals indicator */
+            write_bit(0);
+
+            /* copy literals length */
+            write_interlaced_elias_gamma(length, backwards_mode, FALSE);
+
+            /* copy literals values */
+            for (i = 0; i < length; i++) {
+                write_byte(input_data[input_index]);
+                read_bytes(1, delta);
+            }
+        } else if (optimal->offset == last_offset) {
+            /* copy from last offset indicator */
+            write_bit(0);
+
+            /* copy from last offset length */
+            write_interlaced_elias_gamma(length, backwards_mode, FALSE);
+            read_bytes(length, delta);
+        } else {
+            /* copy from new offset indicator */
+            write_bit(1);
+
+            /* copy from new offset MSB */
+            write_interlaced_elias_gamma((optimal->offset-1)/128+1, backwards_mode, invert_mode);
+
+            /* copy from new offset LSB */
+            if (backwards_mode)
+                write_byte(((optimal->offset-1)%128)<<1);
+            else
+                write_byte((127-(optimal->offset-1)%128)<<1);
+
+            /* copy from new offset length */
+            backtrack = TRUE;
+            write_interlaced_elias_gamma(length-1, backwards_mode, FALSE);
+            read_bytes(length, delta);
+
+            last_offset = optimal->offset;
+        }
+    }
+
+    /* end marker */
+    write_bit(1);
+    write_interlaced_elias_gamma(256, backwards_mode, invert_mode);
+
+    /* done! */
+    return output_data;
+}