4692 - update online help for subx

It now includes details for 8-bit registers. And we'll just use the classic
names for the registers so that the relationships between 8- and 32-bit
versions are more obvious.

1 files changed, 35 insertions, 21 deletions

diff --git a/subx/030---operands.cc b/subx/030---operands.cc
index 196e8556..4015174b 100644
--- a/subx/030---operands.cc
+++ b/subx/030---operands.cc
@@ -72,9 +72,10 @@ void init_operand_type_help() {
     "     Using it as an address gets more involved. For more details,\n"
     "     try reading the help pages for 'base', 'index' and 'scale'.)\n"
     "\n"
-    "For complete details consult the IA-32 software developer's manual, table 2-2,\n"
-    "\"32-bit addressing forms with the ModR/M byte\".\n"
-    "  https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n"
+    "For complete details, spend some time with two tables in the IA-32 software\n"
+    "developer's manual that are also included in this repo:\n"
+    "  - modrm.pdf: volume 2, table 2-2, \"32-bit addressing with the ModR/M byte.\".\n"
+    "  - sib.pdf: volume 2, table 2-3, \"32-bit addressing with the SIB byte.\".\n"
   );
   put(Help, "subop",
     "Additional 3-bit operand for determining the instruction when the opcode is 81, 8f or ff.\n"
@@ -84,34 +85,47 @@ void init_operand_type_help() {
     "3-bit operand specifying a register operand used directly, without any further addressing modes.\n"
   );
   put(Help, "rm32",
-    "32-bit value in register or memory. The precise details of its construction depend on the eponymous 3-bit\n"
-    "'rm32' operand, the 'mod' operand, and also potentially the 'SIB' operands ('scale', 'index' and 'base')\n"
-    "and a displacement ('disp8' or 'disp32').\n"
-    "For complete details consult the IA-32 software developer's manual, table 2-2,\n"
-    "\"32-bit addressing forms with the ModR/M byte\".\n"
-    "  https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n"
+    "32-bit value in register or memory. The precise details of its construction\n"
+    "depend on the eponymous 3-bit 'rm32' operand, the 'mod' operand, and also\n"
+    "potentially the 'SIB' operands ('scale', 'index' and 'base') and a displacement\n"
+    "('disp8' or 'disp32').\n"
+    "\n"
+    "For complete details, spend some time with two tables in the IA-32 software\n"
+    "developer's manual that are also included in this repo:\n"
+    "  - modrm.pdf: volume 2, table 2-2, \"32-bit addressing with the ModR/M byte.\".\n"
+    "  - sib.pdf: volume 2, table 2-3, \"32-bit addressing with the SIB byte.\".\n"
   );
   put(Help, "base",
-    "Additional 3-bit operand (when 'rm32' is 4 unless 'mod' is 3) specifying the register containing an address to look up.\n"
+    "Additional 3-bit operand (when 'rm32' is 4, unless 'mod' is 3) specifying the\n"
+    "register containing an address to look up.\n"
     "This address may be further modified by 'index' and 'scale' operands.\n"
     "  effective address = base + index*scale + displacement (disp8 or disp32)\n"
-    "For complete details consult the IA-32 software developer's manual, table 2-3,\n"
-    "\"32-bit addressing forms with the SIB byte\".\n"
-    "  https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n"
+    "For complete details, spend some time with the IA-32 software developer's manual,\n"
+    "volume 2, table 2-3, \"32-bit addressing with the SIB byte\".\n"
+    "It is included in this repository as 'sib.pdf'.\n"
   );
   put(Help, "index",
-    "Optional 3-bit operand (when 'rm32' is 4 unless 'mod' is 3) that can be added to the 'base' operand to compute the 'effective address' at which to look up memory.\n"
+    "Optional 3-bit operand (when 'rm32' is 4 unless 'mod' is 3) that can be added to\n"
+    "the 'base' operand to compute the 'effective address' at which to look up memory.\n"
     "  effective address = base + index*scale + displacement (disp8 or disp32)\n"
-    "For complete details consult the IA-32 software developer's manual, table 2-3,\n"
-    "\"32-bit addressing forms with the SIB byte\".\n"
-    "  https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n"
+    "For complete details, spend some time with the IA-32 software developer's manual,\n"
+    "volume 2, table 2-3, \"32-bit addressing with the SIB byte\".\n"
+    "It is included in this repository as 'sib.pdf'.\n"
   );
   put(Help, "scale",
-    "Optional 2-bit operand (when 'rm32' is 4 unless 'mod' is 3) that can be multiplied to the 'index' operand before adding the result to the 'base' operand to compute the _effective address_ to operate on.\n"
+    "Optional 2-bit operand (when 'rm32' is 4 unless 'mod' is 3) that encodes a\n"
+    "power of 2 to be multiplied to the 'index' operand before adding the result to\n"
+    "the 'base' operand to compute the _effective address_ to operate on.\n"
     "  effective address = base + index * scale + displacement (disp8 or disp32)\n"
-    "For complete details consult the IA-32 software developer's manual, table 2-3,\n"
-    "\"32-bit addressing forms with the SIB byte\".\n"
-    "  https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n"
+    "\n"
+    "When scale is 0, use index unmodified.\n"
+    "When scale is 1, multiply index by 2.\n"
+    "When scale is 2, multiply index by 4.\n"
+    "When scale is 3, multiply index by 8.\n"
+    "\n"
+    "For complete details, spend some time with the IA-32 software developer's manual,\n"
+    "volume 2, table 2-3, \"32-bit addressing with the SIB byte\".\n"
+    "It is included in this repository as 'sib.pdf'.\n"
   );
   put(Help, "disp8",
     "8-bit value to be added in many instructions.\n"