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Rewrote opcode parsing without bitfield struct

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SChernykh 2019-02-05 20:25:29 +01:00 committed by wowario
parent 26ff420531
commit 0009b32f08
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GPG Key ID: 24DCBE762DE9C111
1 changed files with 21 additions and 14 deletions
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35
src/crypto/variant4_random_math.h
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@ -33,7 +33,7 @@ enum V4_InstructionList
V4_INSTRUCTION_COUNT = RET,
};
// V4_InstructionCompact is used to generate code from random data
// V4_InstructionDefinition is used to generate code from random data
// Every random sequence of bytes is a valid code
//
// There are 8 registers in total:
@ -41,11 +41,11 @@ enum V4_InstructionList
// - 4 constant registers initialized from loop variables
//
// This is why dst_index is 2 bits
struct V4_InstructionCompact
enum V4_InstructionDefinition
{
uint8_t opcode : 3;
uint8_t dst_index : 2;
uint8_t src_index : 3;
V4_OPCODE_BITS = 3,
V4_DST_INDEX_BITS = 2,
V4_SRC_INDEX_BITS = 3,
};
struct V4_Instruction
@ -235,33 +235,40 @@ static inline int v4_random_math_init(struct V4_Instruction* code, const uint64_
{
check_data(&data_index, 1, data, sizeof(data));
struct V4_InstructionCompact op = ((struct V4_InstructionCompact*)data)[data_index++];
const uint8_t c = ((uint8_t*)data)[data_index++];
// MUL = opcodes 0-2
// ADD = opcode 3
// SUB = opcode 4
// ROR/ROL = opcode 5, shift direction is selected randomly
// XOR = opcodes 6-7
uint8_t opcode = (op.opcode <= 2) ? MUL : (op.opcode - 2);
if (op.opcode == 5)
uint8_t opcode = c & ((1 << V4_OPCODE_BITS) - 1);
if (opcode == 5)
{
check_data(&data_index, 1, data, sizeof(data));
opcode = (data[data_index++] >= 0) ? ROR : ROL;
}
else if (op.opcode >= 6)
else if (opcode >= 6)
{
opcode = XOR;
}
else
{
opcode = (opcode <= 2) ? MUL : (opcode - 2);
}
const int a = op.dst_index;
int b = op.src_index;
uint8_t dst_index = (c >> V4_OPCODE_BITS) & ((1 << V4_DST_INDEX_BITS) - 1);
uint8_t src_index = (c >> (V4_OPCODE_BITS + V4_DST_INDEX_BITS)) & ((1 << V4_SRC_INDEX_BITS) - 1);
const int a = dst_index;
int b = src_index;
// Don't do ADD/SUB/XOR with the same register
if (((opcode == ADD) || (opcode == SUB) || (opcode == XOR)) && (a == b))
{
// a is always < 4, so we don't need to check bounds here
b = a + 4;
op.src_index = b;
src_index = b;
}
// Don't do rotation with the same destination twice because it's equal to a single rotation
@ -337,8 +344,8 @@ static inline int v4_random_math_init(struct V4_Instruction* code, const uint64_
inst_data[a] = code_size + (opcode << 8) + ((inst_data[b] & 255) << 16);
code[code_size].opcode = opcode;
code[code_size].dst_index = op.dst_index;
code[code_size].src_index = op.src_index;
code[code_size].dst_index = dst_index;
code[code_size].src_index = src_index;
code[code_size].C = 0;
if (opcode == ADD)