upgrade: PER related changes
git-svn-id: https://asn1c.svn.sourceforge.net/svnroot/asn1c/trunk@1011 59561ff5-6e30-0410-9f3c-9617f08c8826
diff --git a/skeletons/per_support.c b/skeletons/per_support.c
new file mode 100644
index 0000000..506ca78
--- /dev/null
+++ b/skeletons/per_support.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2005 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_system.h>
+#include <per_support.h>
+
+/*
+ * Extract a small number of bits (<= 24) from the specified PER data pointer.
+ */
+int32_t
+per_get_few_bits(asn_per_data_t *pd, int nbits) {
+ size_t off; /* Next after last bit offset */
+ uint32_t accum;
+ uint8_t *buf;
+
+ if(nbits < 0 || pd->nboff + nbits > pd->nbits)
+ return -1;
+ if(nbits == 0)
+ return 0;
+
+ /*
+ * Normalize position indicator.
+ */
+ if(pd->nboff >= 8) {
+ pd->buffer += (pd->nboff >> 3);
+ pd->nbits -= (pd->nboff & ~0x07);
+ pd->nboff &= 0x07;
+ }
+ off = (pd->nboff += nbits);
+ buf = pd->buffer;
+
+ /*
+ * Extract specified number of bits.
+ */
+ if(off <= 8)
+ accum = (buf[0]) >> (8 - off);
+ else if(off <= 16)
+ accum = ((buf[0] << 8) + buf[1]) >> (16 - off);
+ else if(off <= 24)
+ accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off);
+ else if(off <= 31)
+ accum = ((buf[0] << 24) + (buf[1] << 16)
+ + (buf[2] << 8) + (buf[3])) >> (32 - off);
+ else {
+ pd->nboff -= nbits; /* Oops, revert back */
+ return -1;
+ }
+
+ return (accum & ((1 << nbits) - 1));
+}
+
+/*
+ * Extract a large number of bits from the specified PER data pointer.
+ */
+int
+per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int alright, int nbits) {
+ int32_t value;
+
+ if(alright && (nbits & 7)) {
+ /* Perform right alignment of a first few bits */
+ value = per_get_few_bits(pd, nbits & 0x07);
+ if(value < 0) return -1;
+ *dst++ = value; /* value is already right-aligned */
+ nbits &= ~7;
+ }
+
+ while(nbits) {
+ if(nbits >= 24) {
+ value = per_get_few_bits(pd, 24);
+ if(value < 0) return -1;
+ *(dst++) = value >> 16;
+ *(dst++) = value >> 8;
+ *(dst++) = value;
+ nbits -= 24;
+ } else {
+ value = per_get_few_bits(pd, nbits);
+ if(value < 0) return -1;
+ if(nbits & 7) { /* implies alright */
+ value <<= 8 - (nbits & 7),
+ nbits += 8 - (nbits & 7);
+ if(nbits > 24)
+ *dst++ = value >> 24;
+ }
+ if(nbits > 16)
+ *dst++ = value >> 16;
+ if(nbits > 8)
+ *dst++ = value >> 8;
+ *dst++ = value;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Get the length "n" from the stream.
+ */
+ssize_t
+uper_get_length(asn_per_data_t *pd, int ebits, int *repeat) {
+ ssize_t value;
+
+ *repeat = 0;
+
+ if(ebits >= 0) return per_get_few_bits(pd, ebits);
+
+ value = per_get_few_bits(pd, 8);
+ if(value < 0) return -1;
+ if((value & 128) == 0) /* #10.9.3.6 */
+ return (value & 0x7F);
+ if((value & 64) == 0) { /* #10.9.3.7 */
+ value = ((value & 63) << 8) | per_get_few_bits(pd, 8);
+ if(value < 0) return -1;
+ return value;
+ }
+ value &= 63; /* this is "m" from X.691, #10.9.3.8 */
+ if(value < 1 || value > 4)
+ return -1;
+ *repeat = 1;
+ return (16384 * value);
+}
+
+/*
+ * Get the normally small non-negative whole number.
+ * X.691, #10.6
+ */
+ssize_t
+uper_get_nsnnwn(asn_per_data_t *pd) {
+ ssize_t value;
+
+ value = per_get_few_bits(pd, 7);
+ if(value & 64) { /* implicit (value < 0) */
+ value &= 63;
+ value <<= 2;
+ value |= per_get_few_bits(pd, 2);
+ if(value & 128) /* implicit (value < 0) */
+ return -1;
+ if(value == 0)
+ return 0;
+ if(value >= 3)
+ return -1;
+ value = per_get_few_bits(pd, 8 * value);
+ return value;
+ }
+
+ return value;
+}