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, 104 insertions, 74 deletions

diff --git a/subx/016index_addressing.cc b/subx/016index_addressing.cc
index 9fb3e9bb..ef72f710 100644
--- a/subx/016index_addressing.cc
+++ b/subx/016index_addressing.cc
@@ -1,19 +1,25 @@
 //: operating on memory at the address provided by some register plus optional scale and offset
 
-:(scenario add_r32_to_mem_at_r32_with_sib)
-% Reg[EBX].i = 0x10;
-% Reg[EAX].i = 0x2000;
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  01  1c      20                             # add EBX to *EAX
-# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
-# SIB in binary: 00 (scale 1) 100 (no index) 000 (base EAX)
-== 0x2000  # data segment
-01 00 00 00  # 1
-+run: add EBX to r/m32
-+run: effective address is initially 0x00002000 (EAX)
-+run: effective address is 0x00002000
-+run: storing 0x00000011
+:(code)
+void test_add_r32_to_mem_at_r32_with_sib() {
+  Reg[EBX].i = 0x10;
+  Reg[EAX].i = 0x2000;
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  01     1c      20                              \n"  // add EBX to *EAX
+      // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
+      // SIB in binary: 00 (scale 1) 100 (no index) 000 (base EAX)
+      "== 0x2000\n"  // data segment
+      "01 00 00 00\n"  // 0x00000001
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: add EBX to r/m32\n"
+      "run: effective address is initially 0x00002000 (EAX)\n"
+      "run: effective address is 0x00002000\n"
+      "run: storing 0x00000011\n"
+  );
+}
 
 :(before "End Mod 0 Special-cases(addr)")
 case 4:  // exception: mod 0b00 rm 0b100 => incoming SIB (scale-index-base) byte
@@ -46,54 +52,72 @@ uint32_t effective_address_from_sib(uint8_t mod) {
   return addr;
 }
 
-:(scenario add_r32_to_mem_at_base_r32_index_r32)
-% Reg[EBX].i = 0x10;  // source
-% Reg[EAX].i = 0x1ffe;  // dest base
-% Reg[ECX].i = 0x2;  // dest index
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  01  1c      08                             # add EBX to *(EAX+ECX)
-# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
-# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
-== 0x2000  # data segment
-01 00 00 00  # 1
-+run: add EBX to r/m32
-+run: effective address is initially 0x00001ffe (EAX)
-+run: effective address is 0x00002000 (after adding ECX*1)
-+run: storing 0x00000011
+:(code)
+void test_add_r32_to_mem_at_base_r32_index_r32() {
+  Reg[EBX].i = 0x10;  // source
+  Reg[EAX].i = 0x1ffe;  // dest base
+  Reg[ECX].i = 0x2;  // dest index
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  01     1c      08                              \n"  // add EBX to *(EAX+ECX)
+      // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
+      // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
+      "== 0x2000\n"  // data segment
+      "01 00 00 00\n"  // 0x00000001
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: add EBX to r/m32\n"
+      "run: effective address is initially 0x00001ffe (EAX)\n"
+      "run: effective address is 0x00002000 (after adding ECX*1)\n"
+      "run: storing 0x00000011\n"
+  );
+}
 
-:(scenario add_r32_to_mem_at_displacement_using_sib)
-% Reg[EBX].i = 0x10;  // source
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  01  1c      25    00 20 00 00              # add EBX to *0x2000
-# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
-# SIB in binary: 00 (scale 1) 100 (no index) 101 (not EBP but disp32)
-== 0x2000  # data segment
-01 00 00 00  # 1
-+run: add EBX to r/m32
-+run: effective address is initially 0x00002000 (disp32)
-+run: effective address is 0x00002000
-+run: storing 0x00000011
+:(code)
+void test_add_r32_to_mem_at_displacement_using_sib() {
+  Reg[EBX].i = 0x10;  // source
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  01     1c      25    00 20 00 00               \n"  // add EBX to *0x2000
+      // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
+      // SIB in binary: 00 (scale 1) 100 (no index) 101 (not EBP but disp32)
+      "== 0x2000\n"  // data segment
+      "01 00 00 00\n"  // 0x00000001
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: add EBX to r/m32\n"
+      "run: effective address is initially 0x00002000 (disp32)\n"
+      "run: effective address is 0x00002000\n"
+      "run: storing 0x00000011\n"
+  );
+}
 
 //:
 
-:(scenario add_r32_to_mem_at_base_r32_index_r32_plus_disp8)
-% Reg[EBX].i = 0x10;  // source
-% Reg[EAX].i = 0x1ff9;  // dest base
-% Reg[ECX].i = 0x5;  // dest index
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  01  5c      08    02                       # add EBX to *(EAX+ECX+2)
-# ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 100 (dest in SIB)
-# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
-== 0x2000  # data segment
-01 00 00 00  # 1
-+run: add EBX to r/m32
-+run: effective address is initially 0x00001ff9 (EAX)
-+run: effective address is 0x00001ffe (after adding ECX*1)
-+run: effective address is 0x00002000 (after adding disp8)
-+run: storing 0x00000011
+:(code)
+void test_add_r32_to_mem_at_base_r32_index_r32_plus_disp8() {
+  Reg[EBX].i = 0x10;  // source
+  Reg[EAX].i = 0x1ff9;  // dest base
+  Reg[ECX].i = 0x5;  // dest index
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  01     5c      08    02                        \n"  // add EBX to *(EAX+ECX+2)
+      // ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 100 (dest in SIB)
+      // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
+      "== 0x2000\n"  // data segment
+      "01 00 00 00\n"  // 0x00000001
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: add EBX to r/m32\n"
+      "run: effective address is initially 0x00001ff9 (EAX)\n"
+      "run: effective address is 0x00001ffe (after adding ECX*1)\n"
+      "run: effective address is 0x00002000 (after adding disp8)\n"
+      "run: storing 0x00000011\n"
+  );
+}
 
 :(before "End Mod 1 Special-cases(addr)")
 case 4:  // exception: mod 0b01 rm 0b100 => incoming SIB (scale-index-base) byte
@@ -102,22 +126,28 @@ case 4:  // exception: mod 0b01 rm 0b100 => incoming SIB (scale-index-base) byte
 
 //:
 
-:(scenario add_r32_to_mem_at_base_r32_index_r32_plus_disp32)
-% Reg[EBX].i = 0x10;  // source
-% Reg[EAX].i = 0x1ff9;  // dest base
-% Reg[ECX].i = 0x5;  // dest index
-== 0x1  # code segment
-# op  ModR/M  SIB   displacement  immediate
-  01  9c      08    02 00 00 00              # add EBX to *(EAX+ECX+2)
-# ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 100 (dest in SIB)
-# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
-== 0x2000  # data segment
-01 00 00 00  # 1
-+run: add EBX to r/m32
-+run: effective address is initially 0x00001ff9 (EAX)
-+run: effective address is 0x00001ffe (after adding ECX*1)
-+run: effective address is 0x00002000 (after adding disp32)
-+run: storing 0x00000011
+:(code)
+void test_add_r32_to_mem_at_base_r32_index_r32_plus_disp32() {
+  Reg[EBX].i = 0x10;  // source
+  Reg[EAX].i = 0x1ff9;  // dest base
+  Reg[ECX].i = 0x5;  // dest index
+  run(
+      "== 0x1\n"  // code segment
+      // op     ModR/M  SIB   displacement  immediate
+      "  01     9c      08    02 00 00 00               \n"  // add EBX to *(EAX+ECX+2)
+      // ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 100 (dest in SIB)
+      // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX)
+      "== 0x2000\n"  // data segment
+      "01 00 00 00\n"  // 0x00000001
+  );
+  CHECK_TRACE_CONTENTS(
+      "run: add EBX to r/m32\n"
+      "run: effective address is initially 0x00001ff9 (EAX)\n"
+      "run: effective address is 0x00001ffe (after adding ECX*1)\n"
+      "run: effective address is 0x00002000 (after adding disp32)\n"
+      "run: storing 0x00000011\n"
+  );
+}
 
 :(before "End Mod 2 Special-cases(addr)")
 case 4:  // exception: mod 0b10 rm 0b100 => incoming SIB (scale-index-base) byte