Mercurial > repos > blastem
comparison gen_x86.c @ 691:74d636e85bf8
WIP of functions to determine size of x86 instruction to allow patching of arbitrary pieces of code
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sat, 14 Mar 2015 12:05:03 -0700 |
| parents | 7ed1dbb48f61 |
| children | e11e68918691 |
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| 690:fc04781f4d28 | 691:74d636e85bf8 |
|---|---|
| 2067 pop_r(code, RDI); | 2067 pop_r(code, RDI); |
| 2068 #endif | 2068 #endif |
| 2069 pop_r(code, RBP); | 2069 pop_r(code, RBP); |
| 2070 pop_r(code, RBX); | 2070 pop_r(code, RBX); |
| 2071 } | 2071 } |
| 2072 | |
| 2073 uint8_t has_modrm(uint8_t prefix, uint8_t opcode) | |
| 2074 { | |
| 2075 if (!prefix) { | |
| 2076 switch (opcode) | |
| 2077 { | |
| 2078 case OP_JMP: | |
| 2079 case OP_JMP_BYTE: | |
| 2080 case OP_JCC: | |
| 2081 case OP_CALL: | |
| 2082 case OP_RETN: | |
| 2083 case OP_LOOP: | |
| 2084 case OP_MOV_I8R: | |
| 2085 case OP_MOV_IR: | |
| 2086 case OP_PUSHF: | |
| 2087 case OP_POPF: | |
| 2088 case OP_PUSH: | |
| 2089 case OP_POP: | |
| 2090 case OP_CDQ: | |
| 2091 return 0; | |
| 2092 } | |
| 2093 } else if (prefix == PRE_2BYTE) { | |
| 2094 switch (opcode) | |
| 2095 { | |
| 2096 case OP2_JCC: | |
| 2097 return 0; | |
| 2098 } | |
| 2099 } | |
| 2100 return 1; | |
| 2101 } | |
| 2102 | |
| 2103 uint8_t has_sib(uint8_t mod_rm) | |
| 2104 { | |
| 2105 uint8_t mode = mod_rm & 0xC0; | |
| 2106 uint8_t rm = mod_rm & 3; | |
| 2107 | |
| 2108 return mode != MODE_REG_DIRECT && rm == RSP; | |
| 2109 } | |
| 2110 | |
| 2111 uint32_t x86_inst_size(code_ptr start) | |
| 2112 { | |
| 2113 code_ptr code = start; | |
| 2114 uint8_t cont = 1; | |
| 2115 uint8_t prefix = 0; | |
| 2116 uint8_t op_size = SZ_B; | |
| 2117 uint8_t main_op; | |
| 2118 | |
| 2119 while (cont) | |
| 2120 { | |
| 2121 if (*code == PRE_SIZE) { | |
| 2122 op_size = SZ_W; | |
| 2123 } else if (*code == PRE_REX) { | |
| 2124 if (*code & REX_QUAD) { | |
| 2125 op_size = SZ_Q; | |
| 2126 } | |
| 2127 } else if(*code == PRE_2BYTE || PRE_XOP) { | |
| 2128 prefix = *code; | |
| 2129 } else { | |
| 2130 main_op = *code; | |
| 2131 cont = 0; | |
| 2132 } | |
| 2133 code++; | |
| 2134 } | |
| 2135 if (has_modrm(prefix, main_op)) { | |
| 2136 uint8_t mod_rm = *(code++); | |
| 2137 if (has_sib(mod_rm)) { | |
| 2138 uint8_t sib = *(code++); | |
| 2139 } else { | |
| 2140 | |
| 2141 } | |
| 2142 } else { | |
| 2143 } | |
| 2144 | |
| 2145 return code-start; | |
| 2146 } |