aaru-dps/libaaruformat
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Use heuristics to setup table shift.

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This commit is contained in:
Natalia Portillo
2025-10-02 04:40:16 +01:00
parent 05491bd935
commit 5c7610c1c0
3 changed files with 14 additions and 3 deletions
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2
include/aaruformat/structs/options.h
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@@ -219,7 +219,7 @@ typedef struct
bool deduplicate; ///< Storage dedup flag (DDT always exists). true=share identical sector content, false=store
///< each instance.
uint32_t dictionary; ///< LZMA dictionary size in bytes (>= 4096 recommended). Default: 33554432 (32 MiB).
uint8_t table_shift; ///< DDT table shift (multi-level fan-out exponent). Default: 9.
int8_t table_shift; ///< DDT table shift (multi-level fan-out exponent). Default: heuristically calculated.
uint8_t data_shift; ///< Global data shift: low bits encode sector offset inside a block (2^data_shift span).
uint8_t block_alignment; ///< log2 underlying block alignment (2^n bytes). Default: 9 (512 bytes).
bool md5; ///< Generate MD5 checksum (ChecksumAlgorithm::Md5) when finalizing image.

13
src/create.c
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@@ -231,10 +231,21 @@ void *aaruf_create(const char *filepath, const uint32_t media_type, const uint32
ctx->userDataDdtHeader.start = 0;
ctx->userDataDdtHeader.blockAlignmentShift = parsed_options.block_alignment;
ctx->userDataDdtHeader.dataShift = parsed_options.data_shift;
ctx->userDataDdtHeader.tableShift = parsed_options.table_shift;
ctx->userDataDdtHeader.sizeType = 1;
ctx->userDataDdtHeader.entries = ctx->userDataDdtHeader.blocks / (1 << ctx->userDataDdtHeader.tableShift);
if(parsed_options.table_shift == -1)
{
uint64_t total_sectors = user_sectors + overflow_sectors + negative_sectors;
if(total_sectors < 0x8388608ULL)
ctx->userDataDdtHeader.tableShift = 0;
else
ctx->userDataDdtHeader.tableShift = 22;
}
else
ctx->userDataDdtHeader.tableShift = parsed_options.table_shift;
if(ctx->userDataDdtHeader.blocks % (1 << ctx->userDataDdtHeader.tableShift) != 0) ctx->userDataDdtHeader.entries++;
TRACE("Initializing primary/single DDT");

2
src/options.c
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@@ -42,7 +42,7 @@ aaru_options parse_options(const char *options)
aaru_options parsed = {.compress = true,
.deduplicate = true,
.dictionary = 33554432,
.table_shift = 9,
.table_shift = -1,
.data_shift = 12,
.block_alignment = 9,
.md5 = false,