1 files changed, 137 insertions, 0 deletions
diff --git a/apps/tile/gap-buffer.mu b/apps/tile/gap-buffer.mu
new file mode 100644
index 00000000..11cd34b5
--- /dev/null
+++ b/apps/tile/gap-buffer.mu
@@ -0,0 +1,137 @@
+type gap-buffer {
+  left: grapheme-stack
+  right: grapheme-stack
+}
+
+fn initialize-gap-buffer _self: (addr gap-buffer) {
+  var self/esi: (addr gap-buffer) <- copy _self
+  var left/eax: (addr grapheme-stack) <- get self, left
+  initialize-grapheme-stack left, 0x10
+  var right/eax: (addr grapheme-stack) <- get self, right
+  initialize-grapheme-stack right, 0x10
+}
+
+fn render-gap-buffer screen: (addr screen), _gap: (addr gap-buffer) {
+  var gap/esi: (addr gap-buffer) <- copy _gap
+  var left/eax: (addr grapheme-stack) <- get gap, left
+  render-stack-from-bottom left, screen
+  var right/eax: (addr grapheme-stack) <- get gap, right
+  render-stack-from-top right, screen
+}
+
+# dump stack to screen from bottom to top
+# don't move the cursor or anything
+fn render-stack-from-bottom _self: (addr grapheme-stack), screen: (addr screen) {
+  var self/esi: (addr grapheme-stack) <- copy _self
+  var data-ah/edi: (addr handle array grapheme) <- get self, data
+  var _data/eax: (addr array grapheme) <- lookup *data-ah
+  var data/edi: (addr array grapheme) <- copy _data
+  var top-addr/ecx: (addr int) <- get self, top
+  var i/eax: int <- copy 0
+  {
+    compare i, *top-addr
+    break-if->=
+    var g/edx: (addr grapheme) <- index data, i
+    print-grapheme screen, *g
+    i <- increment
+    loop
+  }
+}
+
+# dump stack to screen from top to bottom
+# don't move the cursor or anything
+fn render-stack-from-top _self: (addr grapheme-stack), screen: (addr screen) {
+  var self/esi: (addr grapheme-stack) <- copy _self
+  var data-ah/edi: (addr handle array grapheme) <- get self, data
+  var _data/eax: (addr array grapheme) <- lookup *data-ah
+  var data/edi: (addr array grapheme) <- copy _data
+  var top-addr/ecx: (addr int) <- get self, top
+  var i/eax: int <- copy *top-addr
+  i <- decrement
+  {
+    compare i, 0
+    break-if-<
+    var g/edx: (addr grapheme) <- index data, i
+    print-grapheme screen, *g
+    i <- decrement
+    loop
+  }
+}
+
+fn add-grapheme _self: (addr gap-buffer), g: grapheme {
+  var self/esi: (addr gap-buffer) <- copy _self
+  var left/eax: (addr grapheme-stack) <- get self, left
+  push-grapheme-stack left, g
+}
+
+fn cursor-right _self: (addr gap-buffer) {
+  var self/esi: (addr gap-buffer) <- copy _self
+  var g/ecx: grapheme <- copy 0
+  {
+    var right/eax: (addr grapheme-stack) <- get self, right
+    var tmp/eax: grapheme <- pop-grapheme-stack right
+    g <- copy tmp
+  }
+  {
+    var left/eax: (addr grapheme-stack) <- get self, left
+    push-grapheme-stack left, g
+  }
+}
+
+fn cursor-left _self: (addr gap-buffer) {
+  var self/esi: (addr gap-buffer) <- copy _self
+  var g/ecx: grapheme <- copy 0
+  {
+    var left/eax: (addr grapheme-stack) <- get self, left
+    var tmp/eax: grapheme <- pop-grapheme-stack left
+    g <- copy tmp
+  }
+  {
+    var right/eax: (addr grapheme-stack) <- get self, right
+    push-grapheme-stack right, g
+  }
+}
+
+type grapheme-stack {
+  data: (handle array grapheme)
+  top: int
+}
+
+fn initialize-grapheme-stack _self: (addr grapheme-stack), n: int {
+  var self/esi: (addr grapheme-stack) <- copy _self
+  var d/edi: (addr handle array grapheme) <- get self, data
+  populate d, n
+  var top/eax: (addr int) <- get self, top
+  copy-to *top, 0
+}
+
+fn push-grapheme-stack _self: (addr grapheme-stack), _val: grapheme {
+  var self/esi: (addr grapheme-stack) <- copy _self
+  var top-addr/ecx: (addr int) <- get self, top
+  var data-ah/edx: (addr handle array grapheme) <- get self, data
+  var data/eax: (addr array grapheme) <- lookup *data-ah
+  var top/edx: int <- copy *top-addr
+  var dest-addr/edx: (addr grapheme) <- index data, top
+  var val/eax: grapheme <- copy _val
+  copy-to *dest-addr, val
+  add-to *top-addr, 1
+}
+
+fn pop-grapheme-stack _self: (addr grapheme-stack) -> val/eax: grapheme {
+$pop-grapheme-stack:body: {
+  var self/esi: (addr grapheme-stack) <- copy _self
+  var top-addr/ecx: (addr int) <- get self, top
+  {
+    compare *top-addr, 0
+    break-if->
+    val <- copy 0
+    break $pop-grapheme-stack:body
+  }
+  subtract-from *top-addr, 1
+  var data-ah/edx: (addr handle array grapheme) <- get self, data
+  var data/eax: (addr array grapheme) <- lookup *data-ah
+  var top/edx: int <- copy *top-addr
+  var result-addr/eax: (addr grapheme) <- index data, top
+  val <- copy *result-addr
+}
+}