forceAlloc impl

assets/disk0/home/hdk/load.js

@@ -16,7 +16,7 @@ sys.free(metaArea)
 if (addrToLoad == 0)
     addrToLoad = sys.malloc(imageSize + 4)
 else
-    forceAlloc(addrToLoad, imageSize + 4)
+    sys.forceAlloc(addrToLoad, imageSize + 4)
 
 // writes IMAGE_SIZE and the BINARY_IMAGE directly to the memory
 infile.pread(addrToLoad, imageSize + 4, 8)

tsvm_core/src/net/torvald/tsvm/VM.kt

@@ -45,6 +45,7 @@ class VM(
 
     val memsize = minOf(USER_SPACE_SIZE, _memsize.toLong())
     val MALLOC_UNIT = 64
+    val MALLOC_RESERVED_BLOCKS = 4 // 4*64=256 bytes are always reserved and won't be allocated to a pointer
     private val mallocBlockSize = (memsize / MALLOC_UNIT).toInt()
 
     internal val usermem = UnsafeHelper.allocate(memsize, this)
@@ -218,7 +219,7 @@ class VM(
     }
 
     private fun findEmptySpace(blockSize: Int): Int? {
-        var cursorHead = 0
+        var cursorHead = MALLOC_RESERVED_BLOCKS
         var cursorTail: Int
         val cursorHeadMaxInclusive = mallocBlockSize - blockSize
         while (cursorHead <= cursorHeadMaxInclusive) {
@@ -261,6 +262,19 @@ class VM(
         allocatedBlockCount -= count
     }
 
+    internal fun forceAlloc(ptr: Int, size: Int) {
+        val allocBlocks = ceil(size.toDouble() / MALLOC_UNIT).toInt()
+        val blockStart = ptr / MALLOC_UNIT
+
+        var previouslyUnallocated = 0
+        for (i in blockStart until blockStart + allocBlocks) {
+            if (mallocMap.get(i) == false) previouslyUnallocated++
+            mallocMap.set(i, true)
+        }
+        allocatedBlockCount += previouslyUnallocated
+        mallocSizes[blockStart] = allocBlocks
+    }
+
     internal data class VMNativePtr(val address: Int, val size: Int)
 }
 

tsvm_core/src/net/torvald/tsvm/VMJSR223Delegate.kt

@@ -82,6 +82,7 @@ class VMJSR223Delegate(private val vm: VM) {
     fun nanoTime() = System.nanoTime()
     fun malloc(size: Int) = vm.malloc(size)
     fun free(ptr: Int) = vm.free(ptr)
+    fun forceAlloc(ptr: Int, size: Int) = vm.forceAlloc(ptr, size)
     fun memcpy(from: Int, to: Int, len: Int) {
         val from = from.toLong()
         val to = to.toLong()