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minor optimization: skip one useless conversion operation #482

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minor optimization: skip one useless conversion operation #482

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c25f4b8
minor optimization: skip one useless conversion operation
Cyan4973 Mar 7, 2026
cc687b9
fixed clang-format
Cyan4973 Mar 7, 2026
2a22b38
skip intermediate conversion for all widths
Cyan4973 Mar 7, 2026
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2 changes: 1 addition & 1 deletion src/openzl/compress/graph_registry.c
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,7 @@ const InternalGraphDesc GR_standardGraphs[ZL_PrivateStandardGraphID_end] = {
REGISTER_DYNAMIC_GRAPH(ZL_StandardGraphID_fse, "!zl.fse", ZL_Type_serial, EI_fseDynamicGraph),
REGISTER_DYNAMIC_GRAPH(ZL_StandardGraphID_huffman, "!zl.huffman", ZL_Type_serial | ZL_Type_struct | ZL_Type_numeric, EI_huffmanDynamicGraph),
REGISTER_DYNAMIC_GRAPH(ZL_StandardGraphID_entropy, "!zl.entropy", ZL_Type_serial | ZL_Type_struct | ZL_Type_numeric, EI_entropyDynamicGraph),
REGISTER_SELECTOR(ZL_StandardGraphID_constant, "!zl.constant", SI_selector_constant, ZL_Type_serial | ZL_Type_struct),
REGISTER_SELECTOR(ZL_StandardGraphID_constant, "!zl.constant", SI_selector_constant, ZL_Type_serial | ZL_Type_struct | ZL_Type_numeric),
REGISTER_STATIC_GRAPH(ZL_StandardGraphID_zstd, "!zl.zstd", ZL_Type_serial, ZL_PrivateStandardNodeID_zstd, _1_SUCCESSOR(ZL_PrivateStandardGraphID_serial_store) ),
REGISTER_SELECTOR(ZL_StandardGraphID_bitpack, "!zl.bitpack", SI_selector_bitpack, ZL_Type_serial | ZL_Type_numeric),
REGISTER_STATIC_GRAPH(ZL_StandardGraphID_flatpack, "!zl.flatpack", ZL_Type_serial, ZL_PrivateStandardNodeID_flatpack, _2_SUCCESSORS(ZL_PrivateStandardGraphID_serial_store, ZL_PrivateStandardGraphID_serial_store) ),
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13 changes: 9 additions & 4 deletions src/openzl/compress/selectors/selector_constant.c
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Expand Up @@ -30,6 +30,10 @@ static int isSingleBytePattern(const ZL_Input* inputStream)
*
* Single-byte patterns (0x00, 0xFF, 0x55, etc.) are routed
* to CONSTANT_SERIAL (more efficient).
*
* Note: data arriving at this selector should be verified constant.
* No verification is done here, but if the data is not constant,
* operation will later fail, on reaching the constant node.
*/

ZL_GraphID SI_selector_constant(
Expand All @@ -43,21 +47,22 @@ ZL_GraphID SI_selector_constant(
(void)nbCustomGraphs;

ZL_Type const inType = ZL_Input_type(inputStream);
ZL_ASSERT(inType == ZL_Type_serial || inType == ZL_Type_struct);
ZL_ASSERT(
inType == ZL_Type_serial || inType == ZL_Type_struct
|| inType == ZL_Type_numeric);

/* If all bytes are identical, Serial path is more efficient */
if (ZL_Input_eltWidth(inputStream) > 1
&& isSingleBytePattern(inputStream)) {
if (isSingleBytePattern(inputStream)) {
return ZL_GRAPH_CONSTANT_SERIAL;
}

switch (inType) {
case ZL_Type_serial:
return ZL_GRAPH_CONSTANT_SERIAL;
case ZL_Type_struct:
case ZL_Type_numeric:
return ZL_GRAPH_CONSTANT_FIXED;
/* fallthrough - not supported */
case ZL_Type_numeric:
case ZL_Type_string:
default:
ZL_REQUIRE(0, "Unsupported input type for constant selector");
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2 changes: 1 addition & 1 deletion src/openzl/compress/selectors/selector_constant.h
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Expand Up @@ -9,7 +9,7 @@
ZL_BEGIN_C_DECLS

// .selector_f = SI_selector_constant,
// .inStreamType = ZL_Type_serial | ZL_Type_struct,
// .inStreamType = ZL_Type_serial | ZL_Type_struct | ZL_Type_numeric,
ZL_GraphID SI_selector_constant(
const ZL_Selector* selCtx,
const ZL_Input* inputStream,
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