From fba0a56add2202403ee7329751694687cbca6966 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sun, 14 Mar 2021 22:56:51 -0700
Subject: .

---
 boot.subx                   |  30 ++++++++++++++----------------
 linux/survey_baremetal      | Bin 53166 -> 53229 bytes
 linux/survey_baremetal.subx |  29 ++++++++++++++++++++++++++++-
 3 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/boot.subx b/boot.subx
index b8b34c4a..78680400 100644
--- a/boot.subx
+++ b/boot.subx
@@ -184,26 +184,24 @@
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 
-# cf:
-# disk_error:
+== code
+
+disk_error:
   # print 'D' to top-left of screen to indicate disk error
   # *0xb8000 <- 0x0f44
-  # bx <- 0xb800
-  bb 00 b8
-  # ds <- bx
-  8e db  # 11b/mod 011b/reg/ds 011b/rm/bx
-  # al <- 'D'
-  b0 44
-  # ah <- 0x0f  # white on black
-  b4 0f
-  # bx <- 0
-  bb 00 00
-  # *ds:bx <- ax
-  89 07  # 00b/mod/indirect 000b/reg/ax 111b/rm/bx
-
-e9 fd ff  # loop forever
+  bb/copy-to-bx 0xb800/imm16
+  8e/seg-> 3/mod/direct 3/rm32/bx 3/r32/ds
+  b0/copy-to-al 0x44/imm8/D
+  b4/copy-to-ah 0x0f/imm8/white-on-black
+  bb/copy-to-bx 0/imm16
+  89/<- 0/mod/indirect 7/rm32/bx 0/r32/ax  # *ds:bx <- ax
+  # loop forever
+  {
+    e9/jump loop/disp16  # TODO: make this disp8
+  }
 
 ## GDT: 3 records of 8 bytes each
+== data
 
 # e0:
 # gdt_start:
diff --git a/linux/survey_baremetal b/linux/survey_baremetal
index 0ae468ff..c5aaf0c2 100755
Binary files a/linux/survey_baremetal and b/linux/survey_baremetal differ
diff --git a/linux/survey_baremetal.subx b/linux/survey_baremetal.subx
index 53addef9..7097701b 100644
--- a/linux/survey_baremetal.subx
+++ b/linux/survey_baremetal.subx
@@ -1501,7 +1501,7 @@ $emit-output:check-disp8:
     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
     # . if (eax == false) goto next check
     3d/compare-eax-and  0/imm32/false
-    74/jump-if-=  $emit-output:check-disp32/disp8
+    74/jump-if-=  $emit-output:check-disp16/disp8
 $emit-output:emit-disp8:
     # emit-hex(out, *address - address-of-next-instruction, 1)
     # . . push args
@@ -1516,6 +1516,33 @@ $emit-output:emit-disp8:
     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
     # continue
     e9/jump  $emit-output:word-loop/disp32
+$emit-output:check-disp16:
+    # if (!has-metadata?(word-slice, "disp16")) goto next check
+    # . eax = has-metadata?(edx, "disp16")
+    # . . push args
+    68/push  "disp16"/imm32
+    52/push-edx
+    # . . call
+    e8/call  has-metadata?/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
+    # . if (eax == false) goto next check
+    3d/compare-eax-and  0/imm32/false
+    74/jump-if-=  $emit-output:check-disp32/disp8
+$emit-output:emit-disp16:
+    # emit-hex(out, *address - address-of-next-instruction, 2)
+    # . . push args
+    68/push  2/imm32
+    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy *esi to eax
+    29/subtract                     3/mod/direct    0/rm32/eax    .           .             .           3/r32/ebx   .               .                 # subtract ebx from eax
+    50/push-eax
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
+    # . . call
+    e8/call  emit-hex/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # continue
+    e9/jump  $emit-output:word-loop/disp32
 $emit-output:check-disp32:
     # if (!has-metadata?(word-slice, "disp32")) abort
     # . eax = has-metadata?(edx, "disp32")
-- 
cgit 1.4.1-2-gfad0