Concatenating hex values in C++
I am having trouble concatenating two hex values in C++;
int virtAddr = (machine->mainMemory[ptrPhysicalAddr + 1] << 8) | (machine->mainMemory[ptrPhysicalAddr]);
int physAddr = currentThread->space->GetPhysicalAddress(virtAddr);
For machine->mainMemory[ptrPhysicalAddr + 1], this yields 0x5. For machine->mainMemory[ptrPhysicalAddr], this yields 0x84. I expect the result 0x584. However, I am getting 0xffffff84. I followed this question Concatenate hex numbers in C.
c++ hex bit-manipulation
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
add a comment |
I am having trouble concatenating two hex values in C++;
int virtAddr = (machine->mainMemory[ptrPhysicalAddr + 1] << 8) | (machine->mainMemory[ptrPhysicalAddr]);
int physAddr = currentThread->space->GetPhysicalAddress(virtAddr);
For machine->mainMemory[ptrPhysicalAddr + 1], this yields 0x5. For machine->mainMemory[ptrPhysicalAddr], this yields 0x84. I expect the result 0x584. However, I am getting 0xffffff84. I followed this question Concatenate hex numbers in C.
c++ hex bit-manipulation
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
1
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
1
What is the type ofmainMemory?
– Alan Stokes
Oct 29 '15 at 20:47
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48
add a comment |
I am having trouble concatenating two hex values in C++;
int virtAddr = (machine->mainMemory[ptrPhysicalAddr + 1] << 8) | (machine->mainMemory[ptrPhysicalAddr]);
int physAddr = currentThread->space->GetPhysicalAddress(virtAddr);
For machine->mainMemory[ptrPhysicalAddr + 1], this yields 0x5. For machine->mainMemory[ptrPhysicalAddr], this yields 0x84. I expect the result 0x584. However, I am getting 0xffffff84. I followed this question Concatenate hex numbers in C.
c++ hex bit-manipulation
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
I am having trouble concatenating two hex values in C++;
int virtAddr = (machine->mainMemory[ptrPhysicalAddr + 1] << 8) | (machine->mainMemory[ptrPhysicalAddr]);
int physAddr = currentThread->space->GetPhysicalAddress(virtAddr);
For machine->mainMemory[ptrPhysicalAddr + 1], this yields 0x5. For machine->mainMemory[ptrPhysicalAddr], this yields 0x84. I expect the result 0x584. However, I am getting 0xffffff84. I followed this question Concatenate hex numbers in C.
c++ hex bit-manipulation
c++ hex bit-manipulation
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
edited Nov 19 '18 at 6:42
Cœur
17.8k9106145
17.8k9106145
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
asked Oct 29 '15 at 20:34
mrQWERTYmrQWERTY
1,41932658
1,41932658
1
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
1
What is the type ofmainMemory?
– Alan Stokes
Oct 29 '15 at 20:47
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48
add a comment |
1
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
1
What is the type ofmainMemory?
– Alan Stokes
Oct 29 '15 at 20:47
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48
1
1
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
1
1
What is the type of
mainMemory?– Alan Stokes
Oct 29 '15 at 20:47
What is the type of
mainMemory?– Alan Stokes
Oct 29 '15 at 20:47
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48
add a comment |
1 Answer
1
active
oldest
votes
0x84 is -124. It gets widened to (int)-124 before the bitwise-OR operation (integer promotion). And 0x00000500 | 0xFFFFFF84 is the result you got. Use an unsigned type to prevent sign-extension when widening.
intptr_t virtAddr = (uint8_t(machine->mainMemory[ptrPhysicalAddr + 1]) << 8)
| uint8_t(machine->mainMemory[ptrPhysicalAddr]);
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
1
Is that an inspired guess about the type ofmachine->mainMemory?
– Roddy
Oct 29 '15 at 20:49
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
0x84 is -124. It gets widened to (int)-124 before the bitwise-OR operation (integer promotion). And 0x00000500 | 0xFFFFFF84 is the result you got. Use an unsigned type to prevent sign-extension when widening.
intptr_t virtAddr = (uint8_t(machine->mainMemory[ptrPhysicalAddr + 1]) << 8)
| uint8_t(machine->mainMemory[ptrPhysicalAddr]);
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
1
Is that an inspired guess about the type ofmachine->mainMemory?
– Roddy
Oct 29 '15 at 20:49
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
add a comment |
0x84 is -124. It gets widened to (int)-124 before the bitwise-OR operation (integer promotion). And 0x00000500 | 0xFFFFFF84 is the result you got. Use an unsigned type to prevent sign-extension when widening.
intptr_t virtAddr = (uint8_t(machine->mainMemory[ptrPhysicalAddr + 1]) << 8)
| uint8_t(machine->mainMemory[ptrPhysicalAddr]);
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
1
Is that an inspired guess about the type ofmachine->mainMemory?
– Roddy
Oct 29 '15 at 20:49
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
add a comment |
0x84 is -124. It gets widened to (int)-124 before the bitwise-OR operation (integer promotion). And 0x00000500 | 0xFFFFFF84 is the result you got. Use an unsigned type to prevent sign-extension when widening.
intptr_t virtAddr = (uint8_t(machine->mainMemory[ptrPhysicalAddr + 1]) << 8)
| uint8_t(machine->mainMemory[ptrPhysicalAddr]);
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
0x84 is -124. It gets widened to (int)-124 before the bitwise-OR operation (integer promotion). And 0x00000500 | 0xFFFFFF84 is the result you got. Use an unsigned type to prevent sign-extension when widening.
intptr_t virtAddr = (uint8_t(machine->mainMemory[ptrPhysicalAddr + 1]) << 8)
| uint8_t(machine->mainMemory[ptrPhysicalAddr]);
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
answered Oct 29 '15 at 20:40
Ben VoigtBen Voigt
234k29311570
234k29311570
1
Is that an inspired guess about the type ofmachine->mainMemory?
– Roddy
Oct 29 '15 at 20:49
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
add a comment |
1
Is that an inspired guess about the type ofmachine->mainMemory?
– Roddy
Oct 29 '15 at 20:49
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
1
1
Is that an inspired guess about the type of
machine->mainMemory?– Roddy
Oct 29 '15 at 20:49
Is that an inspired guess about the type of
machine->mainMemory?– Roddy
Oct 29 '15 at 20:49
1
1
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
@Roddy: Not a guess so much as deduction based on the evidence.
– Ben Voigt
Oct 29 '15 at 21:37
add a comment |
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1
size_t and ptrdiff_t are the types you want
– Dieter Lücking
Oct 29 '15 at 20:38
1
What is the type of
mainMemory?– Alan Stokes
Oct 29 '15 at 20:47
@AlanStokes it is a char array
– mrQWERTY
Oct 29 '15 at 20:48