Mu - 021byte_addressing.cc

1 //: SubX mostly deals with instructions operating on 32-bit operands, but we 2 //: still need to deal with raw bytes for strings and so on. 3 4 //: Unfortunately the register encodings when dealing with bytes are a mess. 5 //: We need a special case for them. 6 :(code) 7 string rname_8bit(uint8_t r) { 8 switch (r) { 9 case 0: return "AL"; // lowest byte of EAX 10 case 1: return "CL"; // lowest byte of ECX 11 case 2: return "DL"; // lowest byte of EDX 12 case 3: return "BL"; // lowest byte of EBX 13 case 4: return "AH"; // second lowest byte of EAX 14 case 5: return "CH"; // second lowest byte of ECX 15 case 6: return "DH"; // second lowest byte of EDX 16 case 7: return "BH"; // second lowest byte of EBX 17 default: raise << "invalid 8-bit register " << r << '\n' << end(); return ""; 18 } 19 } 20 21 uint8_t* effective_byte_address(uint8_t modrm) { 22 uint8_t mod = (modrm>>6); 23 uint8_t rm = modrm & 0x7; 24 if (mod == 3) { 25 // select an 8-bit register 26 trace(Callstack_depth+1, "run") << "r/m8 is " << rname_8bit(rm) << end(); 27 return reg_8bit(rm); 28 } 29 // the rest is as usual 30 return mem_addr_u8(effective_address_number(modrm)); 31 } 32 33 uint8_t* reg_8bit(uint8_t rm) { 34 uint8_t* result = reinterpret_cast<uint8_t*>(&Reg[rm & 0x3].i); // _L register 35 if (rm & 0x4) 36 ++result; // _H register; assumes host is little-endian 37 return result; 38 } 39 40 :(before "End Initialize Op Names") 41 put_new(Name, "88", "copy r8 to r8/m8-at-r32"); 42 43 :(code) 44 void test_copy_r8_to_mem_at_r32() { 45 Reg[EBX].i = 0x224488ab; 46 Reg[EAX].i = 0x2000; 47 run( 48 "== code 0x1\n" 49 // op ModR/M SIB displacement immediate 50 " 88 18 \n" // copy BL to the byte at *EAX 51 // ModR/M in binary: 00 (indirect mode) 011 (src BL) 000 (dest EAX) 52 "== data 0x2000\n" 53 "f0 cc bb aa\n" 54 ); 55 CHECK_TRACE_CONTENTS( 56 "run: copy BL to r8/m8-at-r32\n" 57 "run: effective address is 0x00002000 (EAX)\n" 58 "run: storing 0xab\n" 59 ); 60 CHECK_EQ(0xaabbccab, read_mem_u32(0x2000)); 61 } 62 63 :(before "End Single-Byte Opcodes") 64 case 0x88: { // copy r8 to r/m8 65 const uint8_t modrm = next(); 66 const uint8_t rsrc = (modrm>>3)&0x7; 67 trace(Callstack_depth+1, "run") << "copy " << rname_8bit(rsrc) << " to r8/m8-at-r32" << end(); 68 // use unsigned to zero-extend 8-bit value to 32 bits 69 uint8_t* dest = effective_byte_address(modrm); 70 const uint8_t* src = reg_8bit(rsrc); 71 *dest = *src; // Read/write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well. 72 trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*dest) << end(); 73 break; 74 } 75 76 //: 77 78 :(before "End Initialize Op Names") 79 put_new(Name, "8a", "copy r8/m8-at-r32 to r8"); 80 81 :(code) 82 void test_copy_mem_at_r32_to_r8() { 83 Reg[EBX].i = 0xaabbcc0f; // one nibble each of lowest byte set to all 0s and all 1s, to maximize value of this test 84 Reg[EAX].i = 0x2000; 85 run( 86 "== code 0x1\n" 87 // op ModR/M SIB displacement immediate 88 " 8a 18 \n" // copy just the byte at *EAX to BL 89 // ModR/M in binary: 00 (indirect mode) 011 (dest EBX) 000 (src EAX) 90 "== data 0x2000\n" 91 "ab ff ff ff\n" // 0xab with more data in following bytes 92 ); 93 CHECK_TRACE_CONTENTS( 94 "run: copy r8/m8-at-r32 to BL\n" 95 "run: effective address is 0x00002000 (EAX)\n" 96 "run: storing 0xab\n" 97 // remaining bytes of EBX are *not* cleared 98 "run: EBX now contains 0xaabbccab\n" 99 ); 100 } 101 102 :(before "End Single-Byte Opcodes") 103 case 0x8a: { // copy r/m8 to r8 104 const uint8_t modrm = next(); 105 const uint8_t rdest = (modrm>>3)&366; font-weight: bold } /* Name.Constant */ .highlight .nd { color: #555555 } /* Name.Decorator */ .highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */ .highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */ .highlight .nl { color: #336699; font-style: italic } /* Name.Label */ .highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */ .highlight .py { color: #336699; font-weight: bold } /* Name.Property */ .highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */ .highlight .nv { color: #336699 } /* Name.Variable */ .highlight .ow { color: #008800 } /* Operator.Word */ .highlight .w { color: #bbbbbb } /* Text.Whitespace */ .highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */ .highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */ .highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */ .highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */ .highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */ .highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */ .highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */ .highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */ .highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */ .highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */ .highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */ .highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */ .highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */ .highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */ .highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */ .highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */ .highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */ .highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */ .highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */ .highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */ .highlight .vc { color: #336699 } /* Name.Variable.Class */ .highlight .vg { color: #dd7700 } /* Name.Variable.Global */ .highlight .vi { color: #3333bb } /* Name.Variable.Instance */ .highlight .vm { color: #336699 } /* Name.Variable.Magic */ .highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */

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<a href='https://github.com/akkartik/mu/blob/master/038---literal_strings.cc'>https://github.com/akkartik/mu/blob/master/038---literal_strings.cc</a>
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<span id="L1" class="LineNr">  1 </span><span class="Comment">//: Allow instructions to mention literals directly.</span>
<span id="L2" class="LineNr">  2 </span><span class="Comment">//:</span>
<span id="L3" class="LineNr">  3 </span><span class="Comment">//: This layer will transparently move them to the global segment (assumed to</span>
<span id="L4" class="LineNr">  4 </span><span class="Comment">//: always be the second segment).</span>
<span id="L5" class="LineNr">  5 </span>
<span id="L6" class="LineNr">  6 </span><span class="Normal">void</span> <a href='038---literal_strings.cc.html#L6'>test_transform_literal_string</a><span class="Delimiter">()</span> <span class="Delimiter">{</span>
<span id="L7" class="LineNr">  7 </span>  <a href='011run.cc.html#L82'>run</a><span class="Delimiter">(</span>
<span id="L8" class="LineNr">  8 </span>      <span class="Constant">&quot;== code 0x1\n&quot;</span>
<span id="L9" class="LineNr">  9 </span>      <span class="Constant">&quot;b8/copy  \&quot;</span>test\<span class="Constant">&quot;/imm32\n&quot;</span>
<span id="L10" class="LineNr"> 10 </span>      <span class="Constant">&quot;== data 0x2000\n&quot;</span>  <span class="Comment">// need an empty segment</span>
<span id="L11" class="LineNr"> 11 </span>  <span class="Delimiter">);</span>
<span id="L12" class="LineNr"> 12 </span>  <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a><span class="Delimiter">(</span>
<span id="L13" class="LineNr"> 13 </span>      <span class="Constant">&quot;transform: -- move literal strings to data segment\n&quot;</span>
<span id="L14" class="LineNr"> 14 </span>      <span class="Constant">&quot;transform: adding global variable '__subx_global_1' containing \&quot;</span>test\<span class="Constant">&quot;\n&quot;</span>
<span id="L15" class="LineNr"> 15 </span>      <span class="Constant">&quot;transform: <a href='011run.cc.html#L121'>line</a> after transform: 'b8 __subx_global_1'\n&quot;</span>
<span id="L16" class="LineNr"> 16 </span>  <span class="Delimiter">);</span>
<span id="L17" class="LineNr"> 17 </span><span class="Delimiter">}</span>
<span id="L18" class="LineNr"> 18 </span>
<span id="L19" class="LineNr"> 19 </span><span class="Comment">//: We don't rely on any transforms running in previous layers, but this layer</span>
<span id="L20" class="LineNr"> 20 </span><span class="Comment">//: knows about labels and global variables and will emit them for previous</span>
<span id="L21" class="LineNr"> 21 </span><span class="Comment">//: layers to transform.</span>
<span id="L22" class="LineNr"> 22 </span><span class="Delimiter">:(after &quot;Begin Transforms&quot;)</span>
<span id="L23" class="LineNr"> 23 </span><span class="Special"><a href='031transforms.cc.html#L4'>Transform</a></span><span class="Delimiter">.</span>push_back<span class="Delimiter">(</span><a href='038---literal_strings.cc.html#L30'>transform_literal_strings</a><span class="Delimiter">);</span>
<span id="L24" class="LineNr"> 24 </span>
<span id="L25" class="LineNr"> 25 </span><span class="Delimiter">:(before &quot;End Globals&quot;)</span>
<span id="L26" class="LineNr"> 26 </span><span class="Normal">int</span> <span class="Special">Next_auto_global</span> = <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L27" class="LineNr"> 27 </span><span class="Delimiter">:(before &quot;End Reset&quot;)</span>
<span id="L28" class="LineNr"> 28 </span><span class="Special">Next_auto_global</span> = <span class="Constant">1</span><span class="Delimiter">;</span>
<span id="L29" class="LineNr"> 29 <