REVE1 Logs

Bitwise OR sets each result bit to 1 where either input has a 1 — so 0x69 | 0x55 = 0x7D; it's the go-to operator for turning flag bits on. 0x69 | 0x55 → 0x7D 01101001 (0x69) | 01010101 (0x55) ────────── 01111101 (0x7D) Common uses: 1. Set specific bits: // Set the writ...

Quiz: REVE1 / C Programming | updated: Oct 30, 2026

It lets one adder handle both signed and unsigned numbers, and it has a single zero — unlike sign-magnitude and one's complement. Alternative representations considered: Method -5 (4-bit) Problem Sign-magnitude 1101 (1=neg, 101=5) Need separate add/subtract circuits One'...

Quiz: REVE1 / Number Representations | updated: Oct 30, 2026

The bits are added exactly as for unsigned, but overflow shows up as an impossible sign change: pos + pos → negative, or neg + neg → positive. Positive overflow: Two positive numbers sum to negative Negative overflow: Two negative numbers sum to positive Example (4-bit, range -8...

Quiz: REVE1 / Number Representations | updated: Oct 30, 2026

Bitwise AND sets each result bit to 1 only where both inputs have a 1 — so 0x69 & 0x55 = 0x41. 01101001 (0x69) & 01010101 (0x55) ────────── 01000001 (0x41) Common uses: 1. Extract/mask specific bits: // Get lowest 8 bits int lowByte = value & 0xFF; // Get bit 3 (0 or 1) i...

Quiz: REVE1 / C Programming | updated: Oct 30, 2026

Because do-while — "run the body, then conditionally jump back" — is the only loop shape the hardware directly provides; everything else is built on top of it. Hardware offers straight-line execution plus conditional branches. The do-while pattern maps onto that with zero overhea...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026

Poor ordering scatters padding between members; ordering members from largest/strictest alignment to smallest packs them tightly and shrinks the struct. * Member ordering changes padding: declare fields in decreasing alignment order to shrink the struct. * Because each member mu...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026

Caller-saved: the called function is free to clobber them, so the caller must save anything it still needs. Callee-saved: the function must preserve them, restoring their original values before returning. * Caller-saved may be clobbered by the callee (temporaries); callee-saved...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026

They sign-extend the value in %rax/%eax into the full %rdx:%rax/%edx:%eax pair, building the high half a signed idiv requires. * cqto sign-extends rax into rdx to build the 128-bit rdx:rax dividend; unsigned div zeroes rdx with xor instead. * x86 signed division (idivq) divides...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026

Assembly has no high-level constructs at all — every loop, branch, and data structure dissolves into compares, jumps, and fixed memory offsets that the compiler computes ahead of time. The whole topic reduces to three lessons about what disappears when C becomes machine code: Con...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026

x/NFU address — examine N items, in Format (x=hex, d=dec, i=instruction, s=string…), of Unit size (b/h/w/g = 1/2/4/8 bytes) — starting at address. GDB's x is the Swiss-army knife for inspecting raw memory while reverse-engineering. The count, format, and unit are bundled into one...

Quiz: REVE1 / Translation of C to Assembly | updated: Jul 30, 2026