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endian: read and write little-endian fields byte-wise (unaligned access fault) #129

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Merged
johnpolymath merged 2 commits into from
Sep 18, 2026
Merged

endian: read and write little-endian fields byte-wise (unaligned access fault) #129

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eecc8e6
endian: read and write little-endian fields byte-wise
rosterloh Sep 14, 2026
66507a5
Merge branch 'main' into endian-unaligned
johnpolymath Sep 17, 2026
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52 changes: 40 additions & 12 deletions pstop_c/pstop/src/pstop/endian.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,12 @@
uint16_t
read_uint16_le(const uint8_t *data, size_t *pos)
{
const uint16_t *bytes = (const uint16_t *)(data + *pos);
const uint8_t *bytes = data + *pos;
*pos = *pos + 2U;
return *bytes;
uint16_t b0 = (uint16_t)bytes[0];
uint16_t b1 = (uint16_t)bytes[1];
uint16_t val = (uint16_t)(b0 | (b1 << 8U));
return val;
}

uint16_t
Expand All @@ -25,9 +28,14 @@ read_uint16_be(const uint8_t *data, size_t *pos)
uint32_t
read_uint32_le(const uint8_t *data, size_t *pos)
{
const uint32_t *bytes = (const uint32_t *)(data + *pos);
const uint8_t *bytes = data + *pos;
*pos = *pos + 4U;
return *bytes;
uint32_t b0 = (uint32_t)bytes[0];
uint32_t b1 = (uint32_t)bytes[1];
uint32_t b2 = (uint32_t)bytes[2];
uint32_t b3 = (uint32_t)bytes[3];
uint32_t val = b0 | (b1 << 8U) | (b2 << 16U) | (b3 << 24U);
return val;
}

uint32_t
Expand All @@ -46,9 +54,18 @@ read_uint32_be(const uint8_t *data, size_t *pos)
uint64_t
read_uint64_le(const uint8_t *data, size_t *pos)
{
const uint64_t *bytes = (const uint64_t *)(data + *pos);
const uint8_t *bytes = data + *pos;
*pos = *pos + 8U;
return *bytes;
uint64_t b0 = (uint64_t)bytes[0];
uint64_t b1 = (uint64_t)bytes[1];
uint64_t b2 = (uint64_t)bytes[2];
uint64_t b3 = (uint64_t)bytes[3];
uint64_t b4 = (uint64_t)bytes[4];
uint64_t b5 = (uint64_t)bytes[5];
uint64_t b6 = (uint64_t)bytes[6];
uint64_t b7 = (uint64_t)bytes[7];
uint64_t val = b0 | (b1 << 8U) | (b2 << 16U) | (b3 << 24U) | (b4 << 32U) | (b5 << 40U) | (b6 << 48U) | (b7 << 56U);
return val;
}

uint64_t
Expand All @@ -71,9 +88,10 @@ read_uint64_be(const uint8_t *data, size_t *pos)
void
write_uint16_le(uint16_t value, uint8_t *data, size_t *pos)
{
uint16_t *bytes = (uint16_t *)(data + *pos);
uint8_t *bytes = data + *pos;
*pos = *pos + 2U;
*bytes = value;
bytes[0] = (uint8_t)(value & 0xFFU);
bytes[1] = (uint8_t)((value >> 8U) & 0xFFU);
}

void
Expand All @@ -88,9 +106,12 @@ write_uint16_be(uint16_t value, uint8_t *data, size_t *pos)
void
write_uint32_le(uint32_t value, uint8_t *data, size_t *pos)
{
uint32_t *bytes = (uint32_t *)(data + *pos);
uint8_t *bytes = data + *pos;
*pos = *pos + 4U;
*bytes = value;
bytes[0] = (uint8_t)(value & 0xFFU);
bytes[1] = (uint8_t)((value >> 8U) & 0xFFU);
bytes[2] = (uint8_t)((value >> 16U) & 0xFFU);
bytes[3] = (uint8_t)((value >> 24U) & 0xFFU);
}

void
Expand All @@ -107,9 +128,16 @@ write_uint32_be(uint32_t value, uint8_t *data, size_t *pos)
void
write_uint64_le(uint64_t value, uint8_t *data, size_t *pos)
{
uint64_t *bytes = (uint64_t *)(data + *pos);
uint8_t *bytes = data + *pos;
*pos = *pos + 8U;
*bytes = value;
bytes[0] = (uint8_t)(value & 0xFFU);
bytes[1] = (uint8_t)((value >> 8U) & 0xFFU);
bytes[2] = (uint8_t)((value >> 16U) & 0xFFU);
bytes[3] = (uint8_t)((value >> 24U) & 0xFFU);
bytes[4] = (uint8_t)((value >> 32U) & 0xFFU);
bytes[5] = (uint8_t)((value >> 40U) & 0xFFU);
bytes[6] = (uint8_t)((value >> 48U) & 0xFFU);
bytes[7] = (uint8_t)((value >> 56U) & 0xFFU);
}

void
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