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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - 016index_addressing.cc</title> <meta name="Generator" content="Vim/8.1"> <meta name="plugin-version" content="vim8.1_v1"> <meta name="syntax" content="cpp"> <meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> <meta name="colorscheme" content="minimal-light"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/master/016index_addressing.cc'>https://github.com/akkartik/mu/blob/master/016index_addressing.cc</a> <pre id='vimCodeElement'> 1 //: operating on memory at the address provided by some register plus optional scale and offset 2 3 :(code) 4 void <a href='016index_addressing.cc.html#L4'>test_add_r32_to_mem_at_r32_with_sib</a>() { 5 <a href='010---vm.cc.html#L25'>Reg</a>[EBX].i = 0x10; 6 <a href='010---vm.cc.html#L25'>Reg</a>[EAX].i = 0x2000; 7 <a href='011run.cc.html#L82'>run</a>( 8 "== code 0x1\n" 9 // op ModR/M SIB displacement immediate 10 " 01 1c 20 \n" // add EBX to *EAX 11 // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) 12 // SIB in binary: 00 (scale 1) 100 (no index) 000 (base EAX) 13 "== data 0x2000\n" 14 "01 00 00 00\n" // 0x00000001 15 ); 16 <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a>( 17 "run: add <a href='010---vm.cc.html#L13'>EBX</a> to r/m32\n" 18 "run: effective address is initially 0x00002000 (<a href='010---vm.cc.html#L10'>EAX</a>)\n" 19 "run: effective address is 0x00002000\n" 20 "run: storing 0x00000011\n" 21 ); 22 } 23 24 :(before "End Mod 0 Special-cases(addr)") 25 case 4: // exception: mod 0b00 rm 0b100 => incoming SIB (scale-index-base) byte 26 addr = <a href='016index_addressing.cc.html#L29'>effective_address_from_sib</a>(mod); 27 break; 28 :(code) 29 uint32_t <a href='016index_addressing.cc.html#L29'>effective_address_from_sib</a>(uint8_t mod) { 30 const uint8_t sib = <a href='010---vm.cc.html#L325'>next</a>(); 31 const uint8_t base = sib&0x7; 32 uint32_t addr = 0; 33 if (base != <a href='010---vm.cc.html#L15'>EBP</a> || mod != 0) { 34 addr = <a href='010---vm.cc.html#L25'>Reg</a>[base].u; 35 <a href='003trace.cc.html#L96'>trace</a>(Callstack_depth+1, "run") << "effective address is initially 0x" << <a href='010---vm.cc.html#L395'>HEXWORD</a> << addr << " (" << <a href='013direct_addressing.cc.html#L136'>rname</a>(base) << ")" << end(); 36 } 37 else { 38 // base == EBP && mod == 0 39 addr = <a href='011run.cc.html#L433'>next32</a>(); // ignore base 40 <a href='003trace.cc.html#L96'>trace</a>(Callstack_depth+1, "run") << "effective address is initially 0x" << <a href='010---vm.cc.html#L395'>HEXWORD</a> << addr << " (<a href='040---tests.cc.html#L82'>disp32</a>)" << end(); 41 } 42 const uint8_t index = (sib>>3)&0x7; 43 if (index == <a href='010---vm.cc.html#L14'>ESP</a>) { 44 // ignore index and scale 45 <a href='003trace.cc.html#L96'>trace</a>(Callstack_depth+1, "run") << "effective address is 0x" << <a href='010---vm.cc.html#L395'>HEXWORD</a> << addr << end(); 46 } 47 else { 48 const uint8_t scale = (1 << (sib>>6)); 49 addr += <a href='010---vm.cc.html#L25'>Reg</a>[index].i*scale; // treat index register as signed. Maybe base as well? But we'll always ensure it's non-negative. 50 <a href='003trace.cc.html#L96'>trace</a>(Callstack_depth+1, "run") << "effective address is 0x" << <a href='010---vm.cc.html#L395'>HEXWORD</a> << addr << " (after adding " << <a href='013direct_addressing.cc.html#L136'>rname</a>(index) << "*" << <a href='010---vm.cc.html#L397'>NUM</a>(scale) << ")" << end(); 51 } 52 return addr; 53 } 54 55 :(code) 56 void <a href='016index_addressing.cc.html#L56'>test_add_r32_to_mem_at_base_r32_index_r32</a>() { 57 <a href='010---vm.cc.html#L25'>Reg</a>[EBX].i = 0x10; // source 58 <a href='010---vm.cc.html#L25'>Reg</a>[EAX].i = 0x1ffe; // dest base 59 <a href='010---vm.cc.html#L25'>Reg</a>[ECX].i = 0x2; // dest index 60 <a href='011run.cc.html#L82'>run</a>( 61 "== code 0x1\n" 62 // op ModR/M SIB displacement immediate 63 " 01 1c 08 \n" // add EBX to *(EAX+ECX) 64 // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) 65 // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) 66 "== data 0x2000\n" 67 "01 00 00 00\n" // 0x00000001 68 ); 69 <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a>( 70 "run: add <a href='010---vm.cc.html#L13'>EBX</a> to r/m32\n" 71 "run: effective address is initially 0x00001ffe (<a href='010---vm.cc.html#L10'>EAX</a>)\n" 72 "run: effective address is 0x00002000 (after adding ECX*1)\n" 73 "run: storing 0x00000011\n" 74 ); 75 } 76 77 :(code) 78 void <a href='016index_addressing.cc.html#L78'>test_add_r32_to_mem_at_displacement_using_sib</a>() { 79 <a href='010---vm.cc.html#L25'>Reg</a>[EBX].i = 0x10; // source 80 <a href='011run.cc.html#L82'>run</a>( 81 "== code 0x1\n" 82 // op ModR/M SIB displacement immediate 83 " 01 1c 25 00 20 00 00 \n" // add EBX to *0x2000 84 // ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) 85 // SIB in binary: 00 (scale 1) 100 (no index) 101 (not EBP but disp32) 86 "== data 0x2000\n" 87 "01 00 00 00\n" // 0x00000001 88 ); 89 <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a>( 90 "run: add <a href='010---vm.cc.html#L13'>EBX</a> to r/m32\n" 91 "run: effective address is initially 0x00002000 (<a href='040---tests.cc.html#L82'>disp32</a>)\n" 92 "run: effective address is 0x00002000\n" 93 "run: storing 0x00000011\n" 94 ); 95 } 96 97 //: 98 99 :(code) 100 void <a href='016index_addressing.cc.html#L100'>test_add_r32_to_mem_at_base_r32_index_r32_plus_disp8</a>() { 101 <a href='010---vm.cc.html#L25'>Reg</a>[EBX].i = 0x10; // source 102 <a href='010---vm.cc.html#L25'>Reg</a>[EAX].i = 0x1ff9; // dest base 103 <a href='010---vm.cc.html#L25'>Reg</a>[ECX].i = 0x5; // dest index 104 <a href='011run.cc.html#L82'>run</a>( 105 "== code 0x1\n" 106 // op ModR/M SIB displacement immediate 107 " 01 5c 08 02 \n" // add EBX to *(EAX+ECX+2) 108 // ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 100 (dest in SIB) 109 // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) 110 "== data 0x2000\n" 111 "01 00 00 00\n" // 0x00000001 112 ); 113 <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a>( 114 "run: add <a href='010---vm.cc.html#L13'>EBX</a> to r/m32\n" 115 "run: effective address is initially 0x00001ff9 (<a href='010---vm.cc.html#L10'>EAX</a>)\n" 116 "run: effective address is 0x00001ffe (after adding ECX*1)\n" 117 "run: effective address is 0x00002000 (after adding disp8)\n" 118 "run: storing 0x00000011\n" 119 ); 120 } 121 122 :(before "End Mod 1 Special-cases(addr)") 123 case 4: // exception: mod 0b01 rm 0b100 => incoming SIB (scale-index-base) byte 124 addr = <a href='016index_addressing.cc.html#L29'>effective_address_from_sib</a>(mod); 125 break; 126 127 //: 128 129 :(code) 130 void <a href='016index_addressing.cc.html#L130'>test_add_r32_to_mem_at_base_r32_index_r32_plus_disp32</a>() { 131 <a href='010---vm.cc.html#L25'>Reg</a>[EBX].i = 0x10; // source 132 <a href='010---vm.cc.html#L25'>Reg</a>[EAX].i = 0x1ff9; // dest base 133 <a href='010---vm.cc.html#L25'>Reg</a>[ECX].i = 0x5; // dest index 134 <a href='011run.cc.html#L82'>run</a>( 135 "== code 0x1\n" 136 // op ModR/M SIB displacement immediate 137 " 01 9c 08 02 00 00 00 \n" // add EBX to *(EAX+ECX+2) 138 // ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 100 (dest in SIB) 139 // SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) 140 "== data 0x2000\n" 141 "01 00 00 00\n" // 0x00000001 142 ); 143 <a href='003trace.cc.html#L292'>CHECK_TRACE_CONTENTS</a>( 144 "run: add <a href='010---vm.cc.html#L13'>EBX</a> to r/m32\n" 145 "run: effective address is initially 0x00001ff9 (<a href='010---vm.cc.html#L10'>EAX</a>)\n" 146 "run: effective address is 0x00001ffe (after adding ECX*1)\n" 147 "run: effective address is 0x00002000 (after adding <a href='040---tests.cc.html#L82'>disp32</a>)\n" 148 "run: storing 0x00000011\n" 149 ); 150 } 151 152 :(before "End Mod 2 Special-cases(addr)") 153 case 4: // exception: mod 0b10 rm 0b100 => incoming SIB (scale-index-base) byte 154 addr = <a href='016index_addressing.cc.html#L29'>effective_address_from_sib</a>(mod); 155 break; </pre> </body> </html>


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