1 files changed, 189 insertions, 0 deletions
diff --git a/src/fspec/bcode.c b/src/fspec/bcode.c
new file mode 100644
index 0000000..0a89260
--- /dev/null
+++ b/src/fspec/bcode.c
@@ -0,0 +1,189 @@
+#include <fspec/bcode.h>
+#include "bcode-internal.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <err.h>
+
+static_assert(sizeof(fspec_off) <= sizeof(((struct fspec_mem*)0)->len), "fspec_off should not be larger than what fspec_mem can represent");
+static_assert(sizeof(enum fspec_op) == sizeof(uint8_t), "enum fspec_op is expected to have size of uint8_t");
+static_assert(sizeof(enum fspec_arg) == sizeof(uint8_t), "enum fspec_arg is expected to have size of uint8_t");
+
+static fspec_off
+arg_data_len(const enum fspec_arg *arg)
+{
+   assert(arg);
+
+   switch (*arg) {
+      case FSPEC_ARG_NUM:
+         return sizeof(fspec_num);
+
+      case FSPEC_ARG_VAR:
+         return sizeof(fspec_var);
+
+      case FSPEC_ARG_STR:
+      case FSPEC_ARG_OFF:
+         return sizeof(fspec_off);
+
+      case FSPEC_ARG_DAT:
+         {
+            struct fspec_mem mem;
+            fspec_arg_get_mem(arg, NULL, &mem);
+            return sizeof(fspec_off) + mem.len;
+         }
+
+      case FSPEC_ARG_EOF:
+         break;
+
+      case FSPEC_ARG_LAST:
+         errx(EXIT_FAILURE, "%s: unexpected argument type %u", __func__, *arg);
+         break;
+   }
+
+   return 0;
+}
+
+static fspec_off
+arg_len(const enum fspec_arg *arg)
+{
+   return sizeof(*arg) + arg_data_len(arg);
+}
+
+void
+fspec_arg_get_mem(const enum fspec_arg *arg, const void *data, struct fspec_mem *out_mem)
+{
+   assert(arg && out_mem);
+
+   switch (*arg) {
+      case FSPEC_ARG_STR:
+         {
+            assert(data);
+            fspec_off off;
+            fspec_strsz len;
+            memcpy(&off, (char*)arg + sizeof(*arg), sizeof(off));
+            memcpy(&len, (char*)data + off, sizeof(len));
+            out_mem->data = (char*)data + off + sizeof(len);
+            out_mem->len = len;
+         }
+         break;
+
+      case FSPEC_ARG_DAT:
+         {
+            fspec_off len;
+            memcpy(&len, (char*)arg + sizeof(*arg), sizeof(len));
+            out_mem->data = (char*)arg + sizeof(*arg) + sizeof(len);
+            out_mem->len = len;
+         }
+         break;
+
+      case FSPEC_ARG_VAR:
+      case FSPEC_ARG_NUM:
+      case FSPEC_ARG_OFF:
+         out_mem->data = (char*)arg + sizeof(*arg);
+         out_mem->len = arg_data_len(arg);
+         break;
+
+      case FSPEC_ARG_EOF:
+         *out_mem = (struct fspec_mem){0};
+         break;
+
+      case FSPEC_ARG_LAST:
+         errx(EXIT_FAILURE, "%s: unexpected argument type %u", __func__, *arg);
+         break;
+   }
+}
+
+fspec_num
+fspec_arg_get_num(const enum fspec_arg *arg)
+{
+   assert(arg);
+   fspec_num v;
+   switch (*arg) {
+      case FSPEC_ARG_NUM:
+         memcpy(&v, arg + sizeof(*arg), sizeof(v));
+         break;
+
+      case FSPEC_ARG_VAR:
+         {
+            fspec_var var;
+            memcpy(&var, arg + sizeof(*arg), sizeof(var));
+            v = var;
+         }
+         break;
+
+      case FSPEC_ARG_DAT:
+      case FSPEC_ARG_OFF:
+         {
+            fspec_off off;
+            memcpy(&off, arg + sizeof(*arg), sizeof(off));
+            v = off;
+         }
+         break;
+
+      case FSPEC_ARG_STR:
+      case FSPEC_ARG_EOF:
+      case FSPEC_ARG_LAST:
+         errx(EXIT_FAILURE, "%s: unexpected argument type %u", __func__, *arg);
+         break;
+   }
+   return v;
+}
+
+const char*
+fspec_arg_get_cstr(const enum fspec_arg *arg, const void *data)
+{
+   assert(arg && *arg == FSPEC_ARG_STR);
+   struct fspec_mem mem;
+   fspec_arg_get_mem(arg, data, &mem);
+   return (const char*)mem.data;
+}
+
+const enum fspec_arg*
+fspec_op_get_arg(const enum fspec_op *start, const void *end, const uint8_t nth, const uint32_t expect)
+{
+   uint8_t i = 0;
+   const enum fspec_arg *arg = NULL;
+   for (const enum fspec_op *op = fspec_op_next(start, end, false); op && i < nth; op = fspec_op_next(op, end, false)) {
+      if (*op != FSPEC_OP_ARG)
+         return NULL;
+
+      arg = (void*)(op + 1);
+      assert(*arg >= 0 && *arg < FSPEC_ARG_LAST);
+      ++i;
+   }
+
+   if (arg && !(expect & (1<<*arg)))
+      errx(EXIT_FAILURE, "got unexpected argument of type %u", *arg);
+
+   return arg;
+}
+
+const enum fspec_arg*
+fspec_arg_next(const enum fspec_arg *arg, const void *end, const uint8_t nth, const uint32_t expect)
+{
+   return fspec_op_get_arg((void*)(arg - 1), end, nth, expect);
+}
+
+const enum fspec_op*
+fspec_op_next(const enum fspec_op *start, const void *end, const bool skip_args)
+{
+   assert(start && end);
+   fspec_off off = sizeof(*start);
+   if ((void*)start < end && *start == FSPEC_OP_ARG)
+      off += arg_len((void*)(start + 1));
+
+   for (const enum fspec_op *op = start + off; (void*)start < end && (void*)op < end; ++op) {
+      if (*op >= FSPEC_OP_LAST)
+         errx(EXIT_FAILURE, "got unexected opcode %u", *op);
+
+      if (skip_args && *op == FSPEC_OP_ARG) {
+         op += arg_len((void*)(op + 1));
+         continue;
+      }
+
+      return op;
+   }
+
+   return NULL;
+}