hash.c File Reference

Hash tables used to resolve legacy model identifiers. More...

#include <stdlib.h>
#include <string.h>
#include "hash.h"

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Macros
#define	UCHAR(x)

Functions
int	samestr (const char *s1, const char *s2)
	Compare two nonempty ASCII identifiers without case sensitivity.
unsigned int	hash (const char *str)
	Map an ASCII identifier to a case-insensitive Fletcher-checksum bucket.
HTtable *	HTcreate ()
	Allocate an empty case-insensitive identifier table.
int	HTinsert (HTtable *ht, char *key, int data)
	Prepend a key/data entry to a hash table without copying its key.
int	HTfind (HTtable *ht, const char *key)
	Look up the most recently inserted case-insensitive key match.
char *	HTfindKey (HTtable *ht, const char *key)
	Retrieve the original stored spelling of a case-insensitive key.
void	HTfree (HTtable *ht)
	Free all hash entries and the table bucket array.

Detailed Description

Hash tables used to resolve legacy model identifiers.

Author

Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com (OpenSWMM maintenance and extensions)

Copyright

Copyright (c) 2026 Caleb Buahin. OpenSWMM contributions only; original EPA SWMM credits are retained.

License

Apache-2.0 for OpenSWMM contributions; original EPA SWMM provenance is retained.

Macro Definition Documentation

UCHAR

#define UCHAR

(

x

)

Value:

(((x) >= 'a' && (x) <= 'z') ? ((x) & ~32) : (x))

Function Documentation

hash()

unsigned int hash

(

const char *

str

)

Map an ASCII identifier to a case-insensitive Fletcher-checksum bucket.

Parameters

[in]

str

Non-null borrowed null-terminated identifier; empty is permitted.

Returns

Bucket index in [0, HTMAXSIZE - 1]. Input storage is unchanged.

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HTcreate()

HTtable * HTcreate

(

void

)

Allocate an empty case-insensitive identifier table.

Returns

Owned zero-initialized HTMAXSIZE bucket array, or NULL on allocation failure.

Note

Release the table and its entries with HTfree(); key strings remain externally owned.

HTfind()

int HTfind	(	HTtable *	ht,
		const char *	key )

Look up the most recently inserted case-insensitive key match.

Parameters

[in]	ht	Non-null borrowed table created by HTcreate().
[in]	key	Non-null borrowed nonempty null-terminated identifier.

Returns

Stored integer value, or NOTFOUND if no entry matches.

Note

No storage is modified or retained; returned values can coincide with NOTFOUND if the caller inserted that sentinel as data.

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HTfindKey()

char * HTfindKey	(	HTtable *	ht,
		const char *	key )

Retrieve the original stored spelling of a case-insensitive key.

Parameters

[in]	ht	Non-null borrowed table created by HTcreate().
[in]	key	Non-null borrowed nonempty null-terminated lookup identifier.

Returns

Borrowed original key pointer, or NULL if no entry matches.

Note

The pointer's lifetime follows the external key owner; the table does not copy, free or grant mutation rights to the stored identifier.

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HTfree()

void HTfree

(

HTtable *

ht

)

Free all hash entries and the table bucket array.

Parameters

[in]

ht

Non-null exclusively owned table created by HTcreate().

Postcondition

Table and entry pointers are invalid; borrowed key strings are not freed. The caller must discard or reset its own ht pointer after this call.

HTinsert()

int HTinsert	(	HTtable *	ht,
		char *	key,
		int	data )

Prepend a key/data entry to a hash table without copying its key.

Parameters

[in,out]	ht	Non-null table created by HTcreate().
[in]	key	Borrowed nonempty null-terminated identifier; it must remain alive and unchanged for the entry's lifetime.
[in]	data	Integer value associated with the identifier.

Returns

One on insertion, zero on bucket/allocation failure.

Note

Duplicate keys are allowed and newest entries are found first. The table owns the entry allocation, but never frees key storage.

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samestr()

int samestr	(	const char *	s1,
		const char *	s2 )

Compare two nonempty ASCII identifiers without case sensitivity.

Parameters

[in]	s1	Non-null borrowed null-terminated first string.
[in]	s2	Non-null borrowed null-terminated second string.

Returns

One for equal strings after ASCII case folding, zero otherwise.

Precondition

Both identifiers are nonempty; the loop reads one character beyond a matching pair before its termination check. No storage is retained.

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