4327

Encapsulate RAM management.

10 files changed, 94 insertions, 58 deletions

diff --git a/subx/010core.cc b/subx/010core.cc
index 3b987ffb..a364f2f6 100644
--- a/subx/010core.cc
+++ b/subx/010core.cc
@@ -70,10 +70,47 @@ uint32_t End_of_program = 0;
 Mem.clear();
 Mem.resize(1024);
 End_of_program = 0;
-:(before "End Includes")
-// depends on Mem being laid out contiguously (so you can't use a map, etc.)
-// and on the host also being little-endian
-#define SET_WORD_IN_MEM(addr, val)  *reinterpret_cast<int32_t*>(&Mem.at(addr)) = val;
+:(code)
+// These helpers depend on Mem being laid out contiguously (so you can't use a
+// map, etc.) and on the host also being little-endian.
+inline uint8_t read_mem_u8(uint32_t addr) {
+  return Mem.at(addr);
+}
+inline int8_t read_mem_i8(uint32_t addr) {
+  return static_cast<int8_t>(Mem.at(addr));
+}
+inline uint32_t read_mem_u32(uint32_t addr) {
+  return *reinterpret_cast<uint32_t*>(&Mem.at(addr));
+}
+inline int32_t read_mem_i32(uint32_t addr) {
+  return *reinterpret_cast<int32_t*>(&Mem.at(addr));
+}
+
+inline uint8_t* mem_addr_u8(uint32_t addr) {
+  return &Mem.at(addr);
+}
+inline int8_t* mem_addr_i8(uint32_t addr) {
+  return reinterpret_cast<int8_t*>(&Mem.at(addr));
+}
+inline uint32_t* mem_addr_u32(uint32_t addr) {
+  return reinterpret_cast<uint32_t*>(&Mem.at(addr));
+}
+inline int32_t* mem_addr_i32(uint32_t addr) {
+  return reinterpret_cast<int32_t*>(&Mem.at(addr));
+}
+
+inline void write_mem_u8(uint32_t addr, uint8_t val) {
+  Mem.at(addr) = val;
+}
+inline void write_mem_i8(uint32_t addr, int8_t val) {
+  Mem.at(addr) = static_cast<uint8_t>(val);
+}
+inline void write_mem_u32(uint32_t addr, uint32_t val) {
+  *reinterpret_cast<uint32_t*>(&Mem.at(addr)) = val;
+}
+inline void write_mem_i32(uint32_t addr, int32_t val) {
+  *reinterpret_cast<int32_t*>(&Mem.at(addr)) = val;
+}
 
 //:: core interpreter loop
 
@@ -172,8 +209,8 @@ void load_program(istream& in, uint32_t addr) {
       raise << "input program truncated mid-byte\n" << end();
       return;
     }
-    Mem.at(addr) = to_byte(c1, c2);
-    trace(99, "load") << addr << " -> " << HEXBYTE << NUM(Mem.at(addr)) << end();
+    write_mem_u8(addr, to_byte(c1, c2));
+    trace(99, "load") << addr << " -> " << HEXBYTE << NUM(read_mem_u8(addr)) << end();
     addr++;
     if (addr >= Mem.size()) Mem.resize(Mem.size()*2);
   }
@@ -218,7 +255,7 @@ uint8_t to_hex_num(char c) {
 }
 
 inline uint8_t next() {
-  return Mem.at(EIP++);
+  return read_mem_u8(EIP++);
 }
 
 // read a 32-bit immediate in little-endian order from the instruction stream
diff --git a/subx/011direct_addressing.cc b/subx/011direct_addressing.cc
index 5ce620ad..1e0375f6 100644
--- a/subx/011direct_addressing.cc
+++ b/subx/011direct_addressing.cc
@@ -42,7 +42,7 @@ int32_t* effective_address(uint8_t modrm) {
   //: other mods are indirect, and they'll set addr appropriately
   assert(addr > 0);
   assert(addr + sizeof(int32_t) <= Mem.size());
-  return reinterpret_cast<int32_t*>(&Mem.at(addr));  // rely on the host itself being in little-endian order
+  return mem_addr_i32(addr);
 }
 
 //:: subtract
@@ -284,14 +284,14 @@ void push(uint32_t val) {
   Reg[ESP].u -= 4;
   trace(2, "run") << "decrementing ESP to 0x" << HEXWORD << Reg[ESP].u << end();
   trace(2, "run") << "pushing value 0x" << HEXWORD << val << end();
-  *reinterpret_cast<uint32_t*>(&Mem.at(Reg[ESP].u)) = val;
+  write_mem_u32(Reg[ESP].u, val);
 }
 
 //:: pop
 
 :(scenario pop_r32)
 % Reg[ESP].u = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0000000a);
+% write_mem_i32(0x60, 0x0000000a);
 # op  ModR/M  SIB   displacement  immediate
   5b                                          # pop stack to EBX
 +run: pop into EBX
@@ -314,7 +314,7 @@ case 0x5f: {  // pop stack into r32
 }
 :(code)
 uint32_t pop() {
-  uint32_t result = *reinterpret_cast<uint32_t*>(&Mem.at(Reg[ESP].u));
+  uint32_t result = read_mem_u32(Reg[ESP].u);
   trace(2, "run") << "popping value 0x" << HEXWORD << result << end();
   Reg[ESP].u += 4;
   trace(2, "run") << "incrementing ESP to 0x" << HEXWORD << Reg[ESP].u << end();
diff --git a/subx/012indirect_addressing.cc b/subx/012indirect_addressing.cc
index 18ca6b5f..2901f8d5 100644
--- a/subx/012indirect_addressing.cc
+++ b/subx/012indirect_addressing.cc
@@ -3,7 +3,7 @@
 :(scenario add_r32_to_mem_at_r32)
 % Reg[3].i = 0x10;
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  18                                     # add EBX to *EAX
 # ModR/M in binary: 00 (indirect mode) 011 (src EAX) 000 (dest EAX)
@@ -27,7 +27,7 @@ case 0:  // indirect addressing
 :(scenario add_mem_at_r32_to_r32)
 % Reg[0].i = 0x60;
 % Reg[3].i = 0x10;
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   03  18                                      # add *EAX to EBX
 # ModR/M in binary: 00 (indirect mode) 011 (src EAX) 000 (dest EAX)
@@ -49,7 +49,7 @@ case 0x03: {  // add r/m32 to r32
 
 :(scenario subtract_r32_from_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 10);
+% write_mem_i32(0x60, 10);
 % Reg[3].i = 1;
 # op  ModR/M  SIB   displacement  immediate
   29  18                                      # subtract EBX from *EAX
@@ -62,7 +62,7 @@ case 0x03: {  // add r/m32 to r32
 
 :(scenario subtract_mem_at_r32_from_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 % Reg[3].i = 10;
 # op  ModR/M  SIB   displacement  immediate
   2b  18                                      # subtract *EAX from EBX
@@ -85,7 +85,7 @@ case 0x2b: {  // subtract r/m32 from r32
 
 :(scenario and_r32_with_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0xff;
 # op  ModR/M  SIB   displacement  immediate
   21  18                                      # and EBX with *EAX
@@ -98,7 +98,7 @@ case 0x2b: {  // subtract r/m32 from r32
 
 :(scenario and_mem_at_r32_with_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x000000ff);
+% write_mem_i32(0x60, 0x000000ff);
 % Reg[3].i = 0x0a0b0c0d;
 # op  ModR/M  SIB   displacement  immediate
   23  18                                      # and *EAX with EBX
@@ -121,7 +121,7 @@ case 0x23: {  // and r/m32 with r32
 
 :(scenario or_r32_with_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0xa0b0c0d0;
 # op  ModR/M  SIB   displacement  immediate
   09  18                                      # or EBX with *EAX
@@ -134,7 +134,7 @@ case 0x23: {  // and r/m32 with r32
 
 :(scenario or_mem_at_r32_with_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0xa0b0c0d0;
 # op  ModR/M  SIB   displacement  immediate
   0b  18                                      # or *EAX with EBX
@@ -157,7 +157,7 @@ case 0x0b: {  // or r/m32 with r32
 
 :(scenario xor_r32_with_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0xaabb0c0d);
+% write_mem_i32(0x60, 0xaabb0c0d);
 % Reg[3].i = 0xa0b0c0d0;
 # op  ModR/M  SIB   displacement  immediate
   31  18                                      # xor EBX with *EAX
@@ -170,7 +170,7 @@ case 0x0b: {  // or r/m32 with r32
 
 :(scenario xor_mem_at_r32_with_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0xa0b0c0d0;
 # op  ModR/M  SIB   displacement  immediate
   33  18                                      # xor *EAX with EBX
@@ -194,7 +194,7 @@ case 0x33: {  // xor r/m32 with r32
 :(scenario not_r32_with_mem_at_r32)
 % Reg[3].i = 0x60;
 # word at 0x60 is 0x0f0f00ff
-% SET_WORD_IN_MEM(0x60, 0x0f0f00ff);
+% write_mem_i32(0x60, 0x0f0f00ff);
 # op  ModR/M  SIB   displacement  immediate
   f7  03                                      # negate *EBX
 # ModR/M in binary: 00 (indirect mode) 000 (unused) 011 (dest EBX)
@@ -206,7 +206,7 @@ case 0x33: {  // xor r/m32 with r32
 
 :(scenario compare_mem_at_r32_with_r32_greater)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0x0a0b0c07;
 # op  ModR/M  SIB   displacement  immediate
   39  18                                      # compare EBX with *EAX
@@ -217,7 +217,7 @@ case 0x33: {  // xor r/m32 with r32
 
 :(scenario compare_mem_at_r32_with_r32_lesser)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c07);
+% write_mem_i32(0x60, 0x0a0b0c07);
 % Reg[3].i = 0x0a0b0c0d;
 # op  ModR/M  SIB   displacement  immediate
   39  18                                      # compare EBX with *EAX
@@ -228,7 +228,7 @@ case 0x33: {  // xor r/m32 with r32
 
 :(scenario compare_mem_at_r32_with_r32_equal)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0x0a0b0c0d;
 # op  ModR/M  SIB   displacement  immediate
   39  18                                      # compare EBX with *EAX
@@ -241,7 +241,7 @@ case 0x33: {  // xor r/m32 with r32
 
 :(scenario compare_r32_with_mem_at_r32_greater)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c07);
+% write_mem_i32(0x60, 0x0a0b0c07);
 % Reg[3].i = 0x0a0b0c0d;
 # op  ModR/M  SIB   displacement  immediate
   3b  18                                      # compare *EAX with EBX
@@ -268,7 +268,7 @@ case 0x3b: {  // set SF if r32 < r/m32
 
 :(scenario compare_r32_with_mem_at_r32_lesser)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0x0a0b0c07;
 # op  ModR/M  SIB   displacement  immediate
   3b  18                                      # compare *EAX with EBX
@@ -279,7 +279,7 @@ case 0x3b: {  // set SF if r32 < r/m32
 
 :(scenario compare_r32_with_mem_at_r32_equal)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0a0b0c0d);
+% write_mem_i32(0x60, 0x0a0b0c0d);
 % Reg[3].i = 0x0a0b0c0d;
 # op  ModR/M  SIB   displacement  immediate
   3b  18                                      # compare *EAX with EBX
@@ -304,7 +304,7 @@ case 0x3b: {  // set SF if r32 < r/m32
 
 :(scenario copy_mem_at_r32_to_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x000000af);
+% write_mem_i32(0x60, 0x000000af);
 # op  ModR/M  SIB   displacement  immediate
   8b  18                                      # copy *EAX to EBX
 # ModR/M in binary: 00 (indirect mode) 011 (src EAX) 000 (dest EAX)
@@ -327,7 +327,7 @@ case 0x8b: {  // copy r32 to r/m32
 
 :(scenario jump_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 8);
+% write_mem_i32(0x60, 8);
 # op  ModR/M  SIB   displacement  immediate
   ff  20                                      # jump to *EAX
 # ModR/M in binary: 00 (indirect mode) 100 (jump to r/m32) 000 (src EAX)
@@ -361,7 +361,7 @@ case 0xff: {
 
 :(scenario push_mem_at_r32)
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x000000af);
+% write_mem_i32(0x60, 0x000000af);
 % Reg[ESP].u = 0x14;
 # op  ModR/M  SIB   displacement  immediate
   ff  30                                      # push *EAX to stack
@@ -384,7 +384,7 @@ case 6: {  // push r/m32 to stack
 :(scenario pop_mem_at_r32)
 % Reg[0].i = 0x60;
 % Reg[ESP].u = 0x10;
-% SET_WORD_IN_MEM(0x10, 0x00000030);
+% write_mem_i32(0x10, 0x00000030);
 # op  ModR/M  SIB   displacement  immediate
   8f  00                                      # pop stack into *EAX
 # ModR/M in binary: 00 (indirect mode) 000 (pop r/m32) 000 (dest EAX)
@@ -412,7 +412,7 @@ case 0x8f: {  // pop stack into r/m32
 
 :(scenario add_r32_to_mem_at_displacement)
 % Reg[3].i = 0x10;  // source
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  1d            60 00 00 00              # add EBX to *0x60
 # ModR/M in binary: 00 (indirect mode) 011 (src EBX) 101 (dest in disp32)
@@ -431,7 +431,7 @@ case 5:  // exception: mod 0b00 rm 0b101 => incoming disp32
 :(scenario add_r32_to_mem_at_r32_plus_disp8)
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x5e;  // dest
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  58            02                       # add EBX to *(EAX+2)
 # ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 000 (dest EAX)
@@ -458,7 +458,7 @@ case 1:  // indirect + disp8 addressing
 :(scenario add_r32_to_mem_at_r32_plus_negative_disp8)
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x61;  // dest
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  58            ff                       # add EBX to *(EAX-1)
 # ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 000 (dest EAX)
@@ -472,7 +472,7 @@ case 1:  // indirect + disp8 addressing
 :(scenario add_r32_to_mem_at_r32_plus_disp32)
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x5e;  // dest
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  98            02 00 00 00              # add EBX to *(EAX+2)
 # ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 000 (dest EAX)
@@ -499,7 +499,7 @@ case 2:  // indirect + disp32 addressing
 :(scenario add_r32_to_mem_at_r32_plus_negative_disp32)
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x61;  // dest
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  98            ff ff ff ff              # add EBX to *(EAX-1)
 # ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 000 (dest EAX)
diff --git a/subx/013immediate_addressing.cc b/subx/013immediate_addressing.cc
index beb6ad3a..78510535 100644
--- a/subx/013immediate_addressing.cc
+++ b/subx/013immediate_addressing.cc
@@ -34,7 +34,7 @@ case 0x81: {  // combine imm32 with r/m32
 
 :(scenario add_imm32_to_mem_at_r32)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   81  03                          0a 0b 0c 0d  # add 0x0d0c0b0a to *EBX
 # ModR/M in binary: 00 (indirect mode) 000 (add imm32) 011 (dest EBX)
@@ -64,7 +64,7 @@ case 0x2d: {  // subtract imm32 from EAX
 
 :(scenario subtract_imm32_from_mem_at_r32)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 10);
+% write_mem_i32(0x60, 10);
 # op  ModR/M  SIB   displacement  immediate
   81  2b                          01 00 00 00  # subtract 1 from *EBX
 # ModR/M in binary: 00 (indirect mode) 101 (subtract imm32) 011 (dest EBX)
@@ -113,7 +113,7 @@ case 0x25: {  // and imm32 with EAX
 
 :(scenario and_imm32_with_mem_at_r32)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x000000ff);
+% write_mem_i32(0x60, 0x000000ff);
 # op  ModR/M  SIB   displacement  immediate
   81  23                          0a 0b 0c 0d  # and 0x0d0c0b0a with *EBX
 # ModR/M in binary: 00 (indirect mode) 100 (and imm32) 011 (dest EBX)
@@ -162,7 +162,7 @@ case 0x0d: {  // or imm32 with EAX
 
 :(scenario or_imm32_with_mem_at_r32)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0xd0c0b0a0);
+% write_mem_i32(0x60, 0xd0c0b0a0);
 # op  ModR/M  SIB   displacement  immediate
   81  0b                          0a 0b 0c 0d  # or 0x0d0c0b0a with *EBX
 # ModR/M in binary: 00 (indirect mode) 001 (or imm32) 011 (dest EBX)
@@ -209,7 +209,7 @@ case 0x35: {  // xor imm32 with EAX
 
 :(scenario xor_imm32_with_mem_at_r32)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0xd0c0b0a0);
+% write_mem_i32(0x60, 0xd0c0b0a0);
 # op  ModR/M  SIB   displacement  immediate
   81  33                          0a 0b 0c 0d  # xor 0x0d0c0b0a with *EBX
 # ModR/M in binary: 00 (indirect mode) 110 (xor imm32) 011 (dest EBX)
@@ -315,7 +315,7 @@ case 7: {
 
 :(scenario compare_imm32_with_mem_at_r32_greater)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0d0c0b0a);
+% write_mem_i32(0x60, 0x0d0c0b0a);
 # op  ModR/M  SIB   displacement  immediate
   81  3b                          07 0b 0c 0d  # compare 0x0d0c0b07 with *EBX
 # ModR/M in binary: 00 (indirect mode) 111 (compare imm32) 011 (dest EBX)
@@ -325,7 +325,7 @@ case 7: {
 
 :(scenario compare_imm32_with_mem_at_r32_lesser)
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0d0c0b07);
+% write_mem_i32(0x60, 0x0d0c0b07);
 # op  ModR/M  SIB   displacement  immediate
   81  3b                          0a 0b 0c 0d  # compare 0x0d0c0b0a with *EBX
 # ModR/M in binary: 00 (indirect mode) 111 (compare imm32) 011 (dest EBX)
@@ -336,7 +336,7 @@ case 7: {
 :(scenario compare_imm32_with_mem_at_r32_equal)
 % Reg[3].i = 0x0d0c0b0a;
 % Reg[3].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x0d0c0b0a);
+% write_mem_i32(0x60, 0x0d0c0b0a);
 # op  ModR/M  SIB   displacement  immediate
   81  3b                          0a 0b 0c 0d  # compare 0x0d0c0b0a with *EBX
 # ModR/M in binary: 00 (indirect mode) 111 (compare imm32) 011 (dest EBX)
@@ -402,8 +402,8 @@ case 0x68: {
   int32_t val = imm32();
   trace(2, "run") << "push imm32 0x" << HEXWORD << val << end();
   Reg[ESP].u -= 4;
-  *reinterpret_cast<uint32_t*>(&Mem.at(Reg[ESP].u)) = val;
+  write_mem_i32(Reg[ESP].u, val);
   trace(2, "run") << "ESP is now 0x" << HEXWORD << Reg[ESP].u << end();
-  trace(2, "run") << "contents at ESP: 0x" << HEXWORD << *reinterpret_cast<uint32_t*>(&Mem.at(Reg[ESP].u)) << end();
+  trace(2, "run") << "contents at ESP: 0x" << HEXWORD << read_mem_u32(Reg[ESP].u) << end();
   break;
 }
diff --git a/subx/014index_addressing.cc b/subx/014index_addressing.cc
index e811290d..6b07436f 100644
--- a/subx/014index_addressing.cc
+++ b/subx/014index_addressing.cc
@@ -3,7 +3,7 @@
 :(scenario add_r32_to_mem_at_r32_with_sib)
 % Reg[3].i = 0x10;
 % Reg[0].i = 0x60;
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # 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)
@@ -48,7 +48,7 @@ uint32_t effective_address_from_sib(uint8_t mod) {
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x5e;  // dest base
 % Reg[1].i = 0x2;  // dest index
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # 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)
@@ -60,7 +60,7 @@ uint32_t effective_address_from_sib(uint8_t mod) {
 
 :(scenario add_r32_to_mem_at_displacement_using_sib)
 % Reg[3].i = 0x10;  // source
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # op  ModR/M  SIB   displacement  immediate
   01  1c      25    60 00 00 00              # add EBX to *0x60
 # ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB)
@@ -76,7 +76,7 @@ uint32_t effective_address_from_sib(uint8_t mod) {
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x59;  // dest base
 % Reg[1].i = 0x5;  // dest index
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # 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)
@@ -98,7 +98,7 @@ case 4:  // exception: mod 0b01 rm 0b100 => incoming SIB (scale-index-base) byte
 % Reg[3].i = 0x10;  // source
 % Reg[0].i = 0x59;  // dest base
 % Reg[1].i = 0x5;  // dest index
-% SET_WORD_IN_MEM(0x60, 1);
+% write_mem_i32(0x60, 1);
 # 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)
diff --git a/subx/017functions.cc b/subx/017functions.cc
index 08bfb793..13ac41d9 100644
--- a/subx/017functions.cc
+++ b/subx/017functions.cc
@@ -47,7 +47,7 @@ case 2: {  // call function pointer at r/m32
 :(scenario call_mem_at_r32)
 % Reg[ESP].u = 0x64;
 % Reg[EBX].u = 0x10;
-% SET_WORD_IN_MEM(0x10, 0x000000a0);
+% write_mem_i32(0x10, 0x000000a0);
 # op  ModR/M  SIB   displacement  immediate
   ff  13                                       # call function offset at *EBX
   # next EIP is 3
@@ -61,7 +61,7 @@ case 2: {  // call function pointer at r/m32
 
 :(scenario ret)
 % Reg[ESP].u = 0x60;
-% SET_WORD_IN_MEM(0x60, 0x00000010);
+% write_mem_i32(0x60, 0x00000010);
 # op  ModR/M  SIB   displacement  immediate
   c3
 +run: return
diff --git a/subx/019syscalls.cc b/subx/019syscalls.cc
index b83b92db..a43e3b8f 100644
--- a/subx/019syscalls.cc
+++ b/subx/019syscalls.cc
@@ -14,11 +14,10 @@ case 0xcd: {  // int imm8 (software interrupt)
 void process_int80() {
   switch (Reg[EAX].u) {
   case 1:
-    cerr << "result: " << NUM(Mem.at(0x08048000)) << '\n';
     exit(Reg[EBX].u);
     break;
   case 3:
-    read(/*file descriptor*/Reg[EBX].u, /*memory buffer*/&Mem.at(Reg[ECX].u), /*size*/Reg[EDX].u);
+    read(/*file descriptor*/Reg[EBX].u, /*memory buffer*/mem_addr_u8(Reg[ECX].u), /*size*/Reg[EDX].u);
     break;
   }
 }
diff --git a/subx/020elf.cc b/subx/020elf.cc
index a67bfdfe..d5f1e109 100644
--- a/subx/020elf.cc
+++ b/subx/020elf.cc
@@ -85,7 +85,7 @@ void load_segment_from_program_header(uint8_t* elf_contents, size_t size, uint32
   if (size > p_memsz) size = p_memsz;
   info << "blitting file offsets (" << p_offset << ", " << (p_offset+p_filesz) << ") to addresses (" << p_vaddr << ", " << (p_vaddr+p_memsz) << ")\n";
   for (size_t i = 0;  i < p_filesz;  ++i)
-    Mem.at(p_vaddr + i) = elf_contents[p_offset + i];
+    write_mem_u8(p_vaddr+i, elf_contents[p_offset+i]);
   if (End_of_program < p_vaddr+p_memsz)
     End_of_program = p_vaddr+p_memsz;
 }
diff --git a/subx/021translate.cc b/subx/021translate.cc
index b8e5159a..5757805e 100644
--- a/subx/021translate.cc
+++ b/subx/021translate.cc
@@ -43,7 +43,7 @@ void dump_elf(const string& program, const char* filename) {
   ofstream out(filename, ios::binary);
   dump_elf_header(out);
   for (size_t i = 1;  i < End_of_program;  ++i) {
-    char c = Mem.at(i);
+    char c = read_mem_u8(i);
     out.write(&c, sizeof(c));
   }
   out.close();
diff --git a/subx/ex2 b/subx/ex2
index 3bbd979b..3bbd979b 100644..100755
--- a/subx/ex2
+++ b/subx/ex2
Binary files differ