glisp/src/memory.h

#ifndef INCLUDED_MEMORY_H
#define INCLUDED_MEMORY_H

#include <float.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>

// Geneal macros
#ifndef __has_attribute
#    define __has_attribute(attr) 0
#endif

#if __has_attribute(always_inline) && defined(_NDEBUG)
#    define ALWAYS_INLINE inline __attribute__((always_inline))
#else
#    define ALWAYS_INLINE inline
#endif

#if __has_attribute(format)
#    define FORMAT(n, m) __attribute__((format(printf, n, m)))
#else
#    define FORMAT(n, m)
#endif

// Byte order stuff
typedef enum {
    ENDIAN_LITTLE,
    ENDIAN_BIG,
} Endianness;

static ALWAYS_INLINE Endianness ENDIANNESS(void) {
    uint16_t x = 1;
    return *(char *) &x == 1 ? ENDIAN_LITTLE : ENDIAN_BIG;
}

static ALWAYS_INLINE bool LITTLE_ENDIAN_P(void) {
    return ENDIANNESS() == ENDIAN_LITTLE;
}

// General float stuff
#if SIZE_MAX == 0xffffffff
#    define LISP_WORD_BITS 32
#elif SIZE_MAX == 0xffffffffffffffff
#    define LISP_WORD_BITS 64
#else
#    error "Unablem to determine system word size!"
#endif
// Check if we support this system's floating point implementation
#if FLT_RADIX != 2 || FLT_MANT_DIG != 24 || DBL_MANT_DIG != 53 \
    || FLT_MAX_EXP != 128 || DBL_MAX_EXP != 1024
#    error "Floating point implementation not supported."
#endif
typedef float lisp_float32_t;
typedef double lisp_float64_t;

static ALWAYS_INLINE uint32_t FLOAT32_TO_INT_BITS(lisp_float32_t flt) {
    union {
        uint32_t int_val;
        lisp_float32_t flt_val;
    } conv = {.flt_val = flt};
    return conv.int_val;
}

static ALWAYS_INLINE uint64_t FLOAT64_TO_INT_BITS(lisp_float64_t flt) {
    union {
        uint64_t int_val;
        lisp_float64_t flt_val;
    } conv = {.flt_val = flt};
    return conv.int_val;
}

#define FLOAT_TO_INT_BITS(flt)                    \
    _Generic((flt),                               \
        lisp_float32_t: FLOAT32_TO_INT_BITS(flt), \
        lisp_float64_t: FLOAT64_TO_INT_BITS(flt))

static ALWAYS_INLINE lisp_float32_t INT_TO_FLOAT32_BITS(uint32_t i) {
    union {
        uint32_t int_val;
        lisp_float32_t flt_val;
    } conv = {.int_val = i};
    return conv.flt_val;
}

static ALWAYS_INLINE lisp_float64_t INT_TO_FLOAT64_BITS(uint64_t i) {
    union {
        uint64_t int_val;
        lisp_float64_t flt_val;
    } conv = {.int_val = i};
    return conv.flt_val;
}

#define INT_TO_FLOAT_BITS(i)              \
    _Generic((i),                         \
        uint32_t: INT_TO_FLOAT32_BITS(i), \
        uint64_t: INT_TO_FLOAT64_BITS(i))

// Allocator
void *lisp_realloc(void *oldptr, size_t size);
void *lisp_malloc(size_t size);
void *lisp_malloc0(size_t size);
void *lisp_aligned_alloc(size_t alignment, size_t size);
#define lisp_free free

// other useful things
static ALWAYS_INLINE void sub_timespecs(const struct timespec *t1,
                                        const struct timespec *t2,
                                        struct timespec *out) {
    out->tv_sec = t1->tv_sec - t2->tv_sec;
    int32_t nsec = t1->tv_nsec - t2->tv_nsec;
    if (nsec < 0) {
        --out->tv_sec;
        nsec += 1000000000;
    }
    out->tv_nsec = nsec;
}

static ALWAYS_INLINE void add_timespecs(const struct timespec *t1,
                                        const struct timespec *t2,
                                        struct timespec *out) {
    out->tv_sec = t1->tv_sec + t2->tv_sec;
    int32_t nsec = t1->tv_nsec + t2->tv_nsec;
    if (nsec > 1000000000) {
        ++out->tv_sec;
        nsec -= 1000000000;
    }
    out->tv_nsec = nsec;
}

typedef struct {
    // this is actually size + 1 bytes for the null byte
    char *buffer;
    size_t size;
    size_t nchars;
} StringStream;

static inline void string_stream_init(StringStream *restrict stream) {
    stream->buffer = lisp_malloc(1);
    stream->size = 0;
    stream->buffer[stream->size] = '\0';
    stream->nchars = 0;
}

static inline void string_stream_free(StringStream *restrict stream) {
    lisp_free(stream->buffer);
}

static inline void string_stream_steal(StringStream *restrict stream,
                                       char **restrict out,
                                       size_t *restrict out_length) {
    *out = stream->buffer;
    *out_length = stream->nchars;
}

int string_stream_printf(StringStream *restrict stream,
                         const char *restrict format, ...) FORMAT(2, 3);
int string_stream_vprintf(StringStream *restrict stream,
                          const char *restrict format, va_list args);

// Get the next line in BUF starting at *START (or &buf[0] if *START is
// NULL). Store the length of the line in LENGTH. BUF is BUF_LENGTH bytes
// long. Return true if we found another line and false otherwise.
bool strgetline(const char *restrict buf, size_t buf_length,
                const char **restrict start, size_t *restrict length);

#endif