diff --git a/modules.yaml b/modules.yaml index e322286..8d461ba 100644 --- a/modules.yaml +++ b/modules.yaml @@ -88,6 +88,7 @@ kutil: - src/libraries/kutil/include source: - src/libraries/kutil/assert.cpp + - src/libraries/kutil/bip_buffer.cpp - src/libraries/kutil/frame_allocator.cpp - src/libraries/kutil/heap_manager.cpp - src/libraries/kutil/memory.cpp @@ -110,6 +111,7 @@ tests: - kutil source: - src/tests/address_manager.cpp + - src/tests/constexpr_hash.cpp - src/tests/frame_allocator.cpp - src/tests/linked_list.cpp - src/tests/heap_manager.cpp diff --git a/src/libraries/kutil/bip_buffer.cpp b/src/libraries/kutil/bip_buffer.cpp new file mode 100644 index 0000000..af7d475 --- /dev/null +++ b/src/libraries/kutil/bip_buffer.cpp @@ -0,0 +1,95 @@ +#include "kutil/assert.h" +#include "kutil/bip_buffer.h" + +namespace kutil { + +bip_buffer::bip_buffer() : + m_start_a(0), + m_start_b(0), + m_size_a(0), + m_size_b(0), + m_buffer_size(0), + m_buffer(nullptr) + {} + +bip_buffer::bip_buffer(uint8_t *buffer, size_t size) : + m_start_a(0), + m_start_b(0), + m_size_a(0), + m_size_b(0), + m_buffer_size(size), + m_buffer(buffer) + {} + +size_t bip_buffer::reserve(size_t size, void **area) +{ + if (m_size_r) { + *area = nullptr; + return 0; + } + + size_t remaining = 0; + if (m_size_b) { + // If B exists, we're appending there. Get space between + // the end of B and start of A. + remaining = m_start_a - m_start_b - m_size_b; + m_start_r = m_start_b + m_size_b; + } else { + // B doesn't exist, check the space both before and after A. + // If the end of A has enough room for this write, put it there. + remaining = m_buffer_size - m_start_a - m_size_a; + m_start_r = m_start_a + m_size_a; + + // Otherwise use the bigger of the areas in front of and after A + if (remaining < size && m_start_a > remaining) { + remaining = m_start_a; + m_start_r = 0; + } + } + + if (!remaining) { + *area = nullptr; + return 0; + } + + m_size_r = (remaining < size) ? remaining : size; + *area = &m_buffer[m_start_r]; + return m_size_r; +} + +void bip_buffer::commit(size_t size) +{ + kassert(size <= m_size_r, "Tried to commit more than reserved"); + + if (m_start_r == m_start_a + m_size_a) { + // We were adding to A + m_size_a += size; + } else { + // We were adding to B + kassert(m_start_r == m_start_b + m_size_b, "Bad m_start_r!"); + m_size_b += size; + } + + m_start_r = m_size_r = 0; +} + +size_t bip_buffer::get_block(void **area) const +{ + *area = m_size_a ? &m_buffer[m_start_a] : nullptr; + return m_size_a; +} + +void bip_buffer::consume(size_t size) +{ + kassert(size <= m_size_a, "Consumed more bytes than exist in A"); + if (size >= m_size_a) { + m_size_a = m_size_b; + m_start_a = m_start_b; + m_size_b = m_start_b = 0; + } else { + m_size_a -= size; + m_start_a += size; + } +} + +} // namespace kutil diff --git a/src/libraries/kutil/include/kutil/bip_buffer.h b/src/libraries/kutil/include/kutil/bip_buffer.h new file mode 100644 index 0000000..f2d55db --- /dev/null +++ b/src/libraries/kutil/include/kutil/bip_buffer.h @@ -0,0 +1,59 @@ +#pragma once +/// \file bip_buffer.h +/// A Bip Buffer (bipartite circular buffer). For more on the Bip Buffer structure, see +/// https://www.codeproject.com/Articles/3479/The-Bip-Buffer-The-Circular-Buffer-with-a-Twist + +#include +#include + +namespace kutil { + +class bip_buffer +{ +public: + /// Default constructor. Creates a zero-size buffer. + bip_buffer(); + + /// Constructor. + bip_buffer(uint8_t *buffer, size_t size); + + /// Reserve an area of buffer for a write. + /// \arg size Requested size, in bytes + /// \arg area [out] Pointer to returned area + /// \returns Size of returned area, in bytes, or 0 on failure + size_t reserve(size_t size, void **area); + + /// Commit a pending write started by reserve() + /// \arg size Amount of data used, in bytes + void commit(size_t size); + + /// Get a pointer to a block of data in the buffer. + /// \arg area [out] Pointer to the retuned area + /// \returns Size of the returned area, in bytes + size_t get_block(void **area) const; + + /// Mark a number of bytes as consumed, freeing buffer space + /// \arg size Number of bytes to consume + void consume(size_t size); + + /// Get total amount of data in the buffer. + /// \returns Number of bytes committed to the buffer + inline size_t size() const { return m_size_a + m_size_b; } + + /// Get total amount of free buffer remaining + /// \returns Number of bytes of buffer that are free + inline size_t free_space() const { return m_buffer_size - size(); } + +private: + size_t m_start_a; + size_t m_start_b; + size_t m_start_r; + size_t m_size_a; + size_t m_size_b; + size_t m_size_r; + + const size_t m_buffer_size; + uint8_t * const m_buffer; +}; + +} // namespace kutil diff --git a/src/libraries/kutil/include/kutil/constexpr_hash.h b/src/libraries/kutil/include/kutil/constexpr_hash.h new file mode 100644 index 0000000..9fab0f1 --- /dev/null +++ b/src/libraries/kutil/include/kutil/constexpr_hash.h @@ -0,0 +1,38 @@ +#pragma once +/// \file constexpr_hash.h +/// A complile-time hashing function + +#include +#include + +namespace kutil { + +constexpr static const uint8_t pearson_hash_table[256] = { + 0x76,0x07,0xbe,0x47,0xcf,0x41,0x0a,0xe8,0x01,0x5c,0x9f,0xc5,0x24,0x63,0x9a,0x85, + 0x39,0x2c,0xe2,0x34,0xb9,0xf2,0xae,0x40,0x10,0x90,0x94,0xd1,0x98,0x2d,0x16,0xfd, + 0xc6,0x48,0x0d,0xce,0x74,0x43,0x28,0xf9,0x61,0x12,0xd0,0xcd,0xd8,0xd7,0xa8,0x78, + 0x73,0x70,0xcc,0x1e,0x17,0xa7,0x87,0x38,0x68,0x91,0xc1,0x04,0x3f,0xf5,0xde,0xa3, + 0x8a,0xe5,0x9b,0xec,0x97,0xd5,0x71,0x4a,0x20,0xca,0xc8,0xc4,0x83,0x53,0xe7,0x7b, + 0x64,0x31,0x06,0xe0,0x7a,0xb6,0x52,0x8c,0xba,0x58,0xcb,0xb5,0x37,0x51,0x59,0xa1, + 0x11,0xe3,0x5a,0xdb,0xe1,0x6d,0x46,0x62,0xaf,0xbd,0x57,0xb8,0x0e,0xf4,0xdd,0xa6, + 0x45,0xf8,0x35,0x42,0x56,0xdf,0xad,0x80,0xb2,0x0b,0x5b,0xd4,0x86,0xb3,0xf0,0xc9, + 0x3c,0xa5,0xc0,0x8e,0x55,0x77,0xeb,0x36,0x79,0xab,0x4c,0x25,0xed,0xa9,0x75,0x8f, + 0xee,0xc2,0x72,0x8b,0x60,0x2a,0xfa,0x32,0xe9,0xda,0x03,0x1b,0x27,0x69,0x18,0x9e, + 0x88,0x96,0x54,0x81,0x30,0x22,0x7c,0x4f,0xc7,0xef,0x5d,0xa4,0x67,0x44,0xc3,0x99, + 0xbb,0xd3,0x8d,0x65,0xb1,0x82,0x09,0x1a,0x13,0xd9,0x9c,0x4d,0xb0,0xfc,0xac,0xbc, + 0x6a,0x29,0x95,0x19,0x92,0xaa,0x49,0x7d,0x3b,0xfb,0x50,0xb7,0xf3,0x5e,0x3e,0x6b, + 0x3a,0x14,0x2b,0xb4,0xfe,0xe6,0x93,0x23,0xd6,0x1f,0xd2,0x0c,0x1d,0x9d,0x6c,0x66, + 0x1c,0x89,0xbf,0xf6,0xff,0x6f,0x84,0x6e,0x2e,0xea,0x21,0xf7,0x7f,0x33,0xf1,0xe4, + 0x3d,0x0f,0x05,0x08,0x4e,0xa2,0xa0,0x2f,0xdc,0x00,0x5f,0x15,0x7e,0x02,0x4b,0x26 +}; + +constexpr inline uint8_t pearson_hash_8(const char *s, uint8_t inv) { + return (*s) ? pearson_hash_8(s + 1, pearson_hash_table[inv ^ *s]) : inv; +} + +} // namespace kutil + +constexpr inline uint8_t operator "" _h (const char *s, size_t len) { + return kutil::pearson_hash_8(s, static_cast(len & 0xff)); +} + diff --git a/src/tests/constexpr_hash.cpp b/src/tests/constexpr_hash.cpp new file mode 100644 index 0000000..6c62f14 --- /dev/null +++ b/src/tests/constexpr_hash.cpp @@ -0,0 +1,21 @@ +#include "kutil/constexpr_hash.h" +#include "catch.hpp" + +using namespace kutil; + +TEST_CASE( "constexpr hash", "[hash]" ) +{ + const unsigned hash1 = static_cast("hash1!"_h); + CHECK(hash1 == 210); + + const unsigned hash2 = static_cast("hash1!"_h); + CHECK(hash1 == hash2); + + const unsigned hash3 = static_cast("not hash1!"_h); + CHECK(hash1 != hash3); + CHECK(hash3 == 37); + + const unsigned hash4 = static_cast("another thing that's longer"_h); + CHECK(hash1 != hash4); + CHECK(hash4 == 212); +}