Added nioTSO's EA MicroTalk encoder to the project

library/tools/utkencode/eachunk.h

@@ -0,0 +1,77 @@
+typedef struct EAChunk {
+    uint32_t type;
+    uint8_t *start;
+    uint8_t *ptr;
+    uint8_t *end;
+} EAChunk;
+
+static void chunk_read_bytes(EAChunk *chunk, uint8_t *dest, size_t size)
+{
+    size_t bytes_remaining = chunk->end - chunk->ptr;
+
+    if (bytes_remaining < size) {
+        fprintf(stderr, "error: unexpected end of chunk\n");
+        exit(EXIT_FAILURE);
+    }
+
+    memcpy(dest, chunk->ptr, size);
+    chunk->ptr += size;
+}
+
+static uint32_t chunk_read_u32(EAChunk *chunk)
+{
+    uint8_t dest[4];
+    chunk_read_bytes(chunk, dest, sizeof(dest));
+    return dest[0] | (dest[1] << 8) | (dest[2] << 16) | (dest[3] << 24);
+}
+
+static uint32_t chunk_read_u8(EAChunk *chunk)
+{
+    uint8_t dest;
+    chunk_read_bytes(chunk, &dest, sizeof(dest));
+    return dest;
+}
+
+static uint32_t chunk_read_var_int(EAChunk *chunk)
+{
+    uint8_t dest[4];
+    uint8_t size = chunk_read_u8(chunk);
+
+    if (size > 4) {
+        fprintf(stderr, "error: invalid varint size %u\n", (unsigned)size);
+        exit(EXIT_FAILURE);
+    }
+
+    chunk_read_bytes(chunk, dest, size);
+
+    /* read a big-endian integer of variable length */
+    switch (size) {
+    case 1: return dest[0];
+    case 2: return (dest[0]<<8) | dest[1];
+    case 3: return (dest[0]<<16) | (dest[1] << 8) | dest[2];
+    case 4: return (dest[0]<<24) | (dest[1] << 16) | (dest[2] << 8) | dest[3];
+    default: return 0;
+    }
+}
+
+static EAChunk *read_chunk(FILE *fp)
+{
+    uint32_t size;
+    static EAChunk chunk;
+    static uint8_t buffer[4096];
+
+    chunk.type = read_u32(fp);
+
+    size = read_u32(fp);
+    if (size < 8 || size-8 > sizeof(buffer)) {
+        fprintf(stderr, "error: invalid chunk size %u\n", (unsigned)size);
+        exit(EXIT_FAILURE);
+    }
+
+    size -= 8;
+    read_bytes(fp, buffer, size);
+    chunk.start = chunk.ptr = buffer;
+    chunk.end = buffer+size;
+
+    return &chunk;
+}