5001 - drop the :(scenario) DSL

I've been saying for a while[1][2][3] that adding extra abstractions makes
things harder for newcomers, and adding new notations doubly so. And then
I notice this DSL in my own backyard. Makes me feel like a hypocrite.

[1] https://news.ycombinator.com/item?id=13565743#13570092
[2] https://lobste.rs/s/to8wpr/configuration_files_are_canary_warning
[3] https://lobste.rs/s/mdmcdi/little_languages_by_jon_bentley_1986#c_3miuf2

The implementation of the DSL was also highly hacky:

a) It was happening in the tangle/ tool, but was utterly unrelated to tangling
layers.

b) There were several persnickety constraints on the different kinds of
lines and the specific order they were expected in. I kept finding bugs
where the translator would silently do the wrong thing. Or the error messages
sucked, and readers may be stuck looking at the generated code to figure
out what happened. Fixing error messages would require a lot more code,
which is one of my arguments against DSLs in the first place: they may
be easy to implement, but they're hard to design to go with the grain of
the underlying platform. They require lots of iteration. Is that effort
worth prioritizing in this project?

On the other hand, the DSL did make at least some readers' life easier,
the ones who weren't immediately put off by having to learn a strange syntax.
There were fewer quotes to parse, fewer backslash escapes.

Anyway, since there are also people who dislike having to put up with strange
syntaxes, we'll call that consideration a wash and tear this DSL out.

---

This commit was sheer drudgery. Hopefully it won't need to be redone with
a new DSL because I grow sick of backslashes.

1 files changed, 70 insertions, 46 deletions

diff --git a/subx/019functions.cc b/subx/019functions.cc
index 66cfe384..7f45167b 100644
--- a/subx/019functions.cc
+++ b/subx/019functions.cc
@@ -3,16 +3,22 @@
 :(before "End Initialize Op Names")
 put_new(Name, "e8", "call disp32 (call)");
 
-:(scenario call_disp32)
-% Reg[ESP].u = 0x64;
-== 0x1
-# op  ModR/M  SIB   displacement  immediate
-  e8                              a0 00 00 00  # call function offset at 0x000000a0
-  # next EIP is 6
-+run: call imm32 0x000000a0
-+run: decrementing ESP to 0x00000060
-+run: pushing value 0x00000006
-+run: jumping to 0x000000a6
+:(code)
+void test_call_disp32() {
+  Reg[ESP].u = 0x64;
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  e8                                 a0 00 00 00 \n"  // call function offset at 0x000000a0
+      // next EIP is 6
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: call imm32 0x000000a0\n"
+      "run: decrementing ESP to 0x00000060\n"
+      "run: pushing value 0x00000006\n"
+      "run: jumping to 0x000000a6\n"
+  );
+}
 
 :(before "End Single-Byte Opcodes")
 case 0xe8: {  // call disp32 relative to next EIP
@@ -28,18 +34,24 @@ case 0xe8: {  // call disp32 relative to next EIP
 
 //:
 
-:(scenario call_r32)
-% Reg[ESP].u = 0x64;
-% Reg[EBX].u = 0x000000a0;
-== 0x1
-# op  ModR/M  SIB   displacement  immediate
-  ff  d3                                       # call function offset at EBX
-  # next EIP is 3
-+run: call to r/m32
-+run: r/m32 is EBX
-+run: decrementing ESP to 0x00000060
-+run: pushing value 0x00000003
-+run: jumping to 0x000000a3
+:(code)
+void test_call_r32() {
+  Reg[ESP].u = 0x64;
+  Reg[EBX].u = 0x000000a0;
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  ff     d3                                      \n"  // call function offset at EBX
+      // next EIP is 3
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: call to r/m32\n"
+      "run: r/m32 is EBX\n"
+      "run: decrementing ESP to 0x00000060\n"
+      "run: pushing value 0x00000003\n"
+      "run: jumping to 0x000000a3\n"
+  );
+}
 
 :(before "End Op ff Subops")
 case 2: {  // call function pointer at r/m32
@@ -52,36 +64,48 @@ case 2: {  // call function pointer at r/m32
   break;
 }
 
-:(scenario call_mem_at_r32)
-% Reg[ESP].u = 0x64;
-% Reg[EBX].u = 0x2000;
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  ff  13                                       # call function offset at *EBX
-  # next EIP is 3
-== 0x2000  # data segment
-a0 00 00 00  # 0xa0
-+run: call to r/m32
-+run: effective address is 0x00002000 (EBX)
-+run: decrementing ESP to 0x00000060
-+run: pushing value 0x00000003
-+run: jumping to 0x000000a3
+:(code)
+void test_call_mem_at_r32() {
+  Reg[ESP].u = 0x64;
+  Reg[EBX].u = 0x2000;
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  ff     13                                      \n"  // call function offset at *EBX
+      // next EIP is 3
+      "== 0x2000\n"  // data segment
+      "a0 00 00 00\n"  // 0x000000a0
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: call to r/m32\n"
+      "run: effective address is 0x00002000 (EBX)\n"
+      "run: decrementing ESP to 0x00000060\n"
+      "run: pushing value 0x00000003\n"
+      "run: jumping to 0x000000a3\n"
+  );
+}
 
 //:: ret
 
 :(before "End Initialize Op Names")
 put_new(Name, "c3", "return from most recent unfinished call (ret)");
 
-:(scenario ret)
-% Reg[ESP].u = 0x2000;
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  c3
-== 0x2000  # data segment
-10 00 00 00  # 0x10
-+run: return
-+run: popping value 0x00000010
-+run: jumping to 0x00000010
+:(code)
+void test_ret() {
+  Reg[ESP].u = 0x2000;
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  c3                                           \n"  // return
+      "== 0x2000\n"  // data segment
+      "10 00 00 00\n"  // 0x00000010
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: return\n"
+      "run: popping value 0x00000010\n"
+      "run: jumping to 0x00000010\n"
+  );
+}
 
 :(before "End Single-Byte Opcodes")
 case 0xc3: {  // return from a call