2 files changed, 75 insertions, 4 deletions
diff --git a/apps/tile/data.mu b/apps/tile/data.mu
index a4ee5b4c..40b24df7 100644
--- a/apps/tile/data.mu
+++ b/apps/tile/data.mu
@@ -51,10 +51,10 @@ type table {
   next: (handle table)
 }
 
-#? type result {
-#?   data: (handle value-stack)
-#?   error: (handle array byte)  # single error message for now
-#? }
+type result {
+  data: value-stack
+  error: (handle array byte)  # single error message for now
+}
 
 # if 'out' is non-null, save the first word of the program there
 fn initialize-program _program: (addr program), out: (addr handle word) {
diff --git a/apps/tile/value-stack.mu b/apps/tile/value-stack.mu
new file mode 100644
index 00000000..f43cd25d
--- /dev/null
+++ b/apps/tile/value-stack.mu
@@ -0,0 +1,71 @@
+type value-stack {
+  data: (handle array value)
+  top: int
+}
+
+fn initialize-value-stack _self: (addr value-stack), n: int {
+  var self/esi: (addr value-stack) <- copy _self
+  var d/edi: (addr handle array value) <- get self, data
+  populate d, n
+  var top/eax: (addr int) <- get self, top
+  copy-to *top, 0
+}
+
+fn clear-value-stack _self: (addr value-stack) {
+  var self/esi: (addr value-stack) <- copy _self
+  var top/eax: (addr int) <- get self, top
+  copy-to *top, 0
+}
+
+fn push-value-stack _self: (addr value-stack), _val: value {
+  var self/esi: (addr value-stack) <- copy _self
+  var top-addr/ecx: (addr int) <- get self, top
+  var data-ah/edx: (addr handle array value) <- get self, data
+  var data/eax: (addr array value) <- lookup *data-ah
+  var top/edx: int <- copy *top-addr
+  var dest-offset/edx: (offset value) <- compute-offset data, top
+  var dest-addr/edx: (addr value) <- index data, dest-offset
+  var val/eax: value <- copy _val
+  copy-to *dest-addr, val
+  add-to *top-addr, 1
+}
+
+fn pop-value-stack _self: (addr value-stack) -> val/eax: value {
+$pop-value-stack:body: {
+  var self/esi: (addr value-stack) <- copy _self
+  var top-addr/ecx: (addr int) <- get self, top
+  {
+    compare *top-addr, 0
+    break-if->
+    val <- copy -1
+    break $pop-value-stack:body
+  }
+  subtract-from *top-addr, 1
+  var data-ah/edx: (addr handle array value) <- get self, data
+  var data/eax: (addr array value) <- lookup *data-ah
+  var top/edx: int <- copy *top-addr
+  var dest-offset/edx: (offset value) <- compute-offset data, top
+  var result-addr/eax: (addr value) <- index data, dest-offset
+  val <- copy *result-addr
+}
+}
+
+fn value-stack-empty? _self: (addr value-stack) -> result/eax: boolean {
+$value-stack-empty?:body: {
+  var self/esi: (addr value-stack) <- copy _self
+  var top/eax: (addr int) <- get self, top
+  compare *top, 0
+  {
+    break-if-=
+    result <- copy 1  # false
+    break $value-stack-empty?:body
+  }
+  result <- copy 0  # false
+}
+}
+
+fn value-stack-length _self: (addr value-stack) -> result/eax: int {
+  var self/esi: (addr value-stack) <- copy _self
+  var top-addr/eax: (addr int) <- get self, top
+  result <- copy *top-addr
+}