#include "memory.h"
#include <lib.h>
#include <stddef.h>

//
//  memory operations
//

int memcmp(const void *restrict vl, const void *restrict vr, size_t n) {
	const unsigned char *l = vl, *r = vr;
	for (; n && *l == *r; n--, l++, r++);
	return n ? *l-*r : 0;
}

void *memcpy(void *restrict dest, const void *restrict src, size_t n) {
	char *d = dest;
	const char *s = src;
	for (; n; n--) *d++ = *s++;
	return dest;
}

volatile void *memcpyv(volatile void *restrict dest, const volatile void *restrict src, size_t n) {
	volatile char *d = dest;
	const volatile char *s = src;
	for (; n; n--) *d++ = *s++;
	return dest;
}

void *memmove(void *dest, const void *src, size_t n) {
	char *d = dest;
	const char *s = src;

	if (d==s) return d;

	if (d<s) {
		for (; n; n--) *d++ = *s++;
	} else {
		while (n) n--, d[n] = s[n];
	}

	return dest;
}

void *memset(void *dest, int c, size_t n) {
	unsigned char *d = dest;
	for (; n; n--) {
		*d++ = c;
	};
	return dest;
}

volatile void *memsetv(volatile void *dest, int c, size_t n) {
	volatile unsigned char *d = dest;
	for (; n; n--) {
		*d++ = c;
	};
	return dest;
}

//
//  string operations
//

int strncmp(const char *restrict lhs, const char *restrict rhs, size_t n) {
	const unsigned char *l=(void *)lhs, *r=(void *)rhs;
	if (!n--) return 0;
	for (; *l && *r && n && *l == *r ; l++, r++, n--);
	return *l - *r;
}

size_t strlen(const char *str) {
	const char *p;
	for (p = str; *p != 0; p++) {}
	return p - str;
}

//
//  string copying and concatenation
//

char *stpcpy(char *restrict dest, const char *restrict src) {
	char *d = dest;
	for (; (*d = *src); d++, src++);
	return d;
}

char *stpncpy(char *restrict dest, const char *restrict src, size_t n) {
	char *d = dest;
	for (; (*d = *src) && n; d++, src++, n--);
	memset(d, 0, n);
	return d;
}

char *strcpy(char *restrict dest, const char *restrict src) {
	char *d = dest;
	for (; (*d = *src); d++, src++);
	return dest;
}

char *strncpy(char *restrict dest, const char *restrict src, size_t n) {
	char *d = dest;
	for (; (*d = *src) && n; d++, src++, n--);
	memset(d, 0, n);
	return dest;
}

char *strcat(char *restrict dest, const char *restrict src) {
	strcpy(dest + strlen(dest), src);
	return dest;
}

//
//  character operations
//

int isspace(int c) {
	switch (c) {
		case ' ':
		case '\t':
		case '\v':
		case '\f':
		case '\r':
		case '\n':
			return 1;
		default:
			return 0;
	}
}

int isdigit(int c) {
	return c >= '0' && c <= '9';
}

//
//  string/numeric conversions
//

#define ATOX(name, type) \
	type name(const char *s) { \
		for (; isspace(*s); s++); \
		int neg = 0; \
		switch (*s) { \
			case '-': \
				neg = 1; \
				/* fallthrough */ \
			case '+': \
				s++; \
				break; \
		} \
		type num = 0; \
		for (; *s == '0'; s++); \
		for (; isdigit(*s); s++) { \
			num *= 10; \
			num += *s - '0'; \
		} \
		return num * (neg ? -1 : 1); \
	}

ATOX(atoi, int)
ATOX(atol, long int)
ATOX(atoll, long long int)

char itoc(int i) {
	if (i < 10) {
		return '0' + i;
	} else {
		return 'a' + (i - 10);
	}
}

int ctoi(char c) {
	if (c >= '0' && c <= '9') {
		return c - '0';
	} else if (c >= 'A' && c <= 'Z') {
		return c - 'A' + 10;
	} else if (c >= 'a' && c <= 'z') {
		return c - 'a' + 10;
	} else {
		return -1;
	}
}


#define UXTOA(type, name)                                  \
	char *name(unsigned type n, char *buffer, int radix) { \
		if (n == 0) {                                      \
			buffer[0] = '0';                               \
			buffer[1] = '\0';                              \
			return buffer + 1;                             \
		}                                                  \
		char *start = buffer;                              \
		for (; n; n /= radix) {                            \
			*buffer++ = itoc(n % radix);                   \
		}                                                  \
		char *buf_end = buffer;                            \
		*buffer-- = '\0';                                  \
		while (buffer > start) {                           \
			char tmp = *start;                             \
			*start++ = *buffer;                            \
			*buffer-- = tmp;                               \
		}                                                  \
		return buf_end;                                    \
	}

UXTOA(int, utoa)
UXTOA(long int, ultoa)
UXTOA(long long int, ulltoa)

#define XTOA(type, name)                           \
	char *name(type n, char *buffer, int radix) {  \
		if (n == 0) {                              \
			buffer[0] = '0';                       \
			buffer[1] = '\0';                      \
			return buffer + 1;                     \
		}                                          \
		if (n < 0) {                               \
			*buffer++ = '-';                       \
			n = -n;                                \
		}                                          \
		char *start = buffer;                      \
		for (; n; n /= radix) {                    \
			*buffer++ = itoc(n % radix);           \
		}                                          \
		char *buf_end = buffer;                    \
		*buffer-- = '\0';                          \
		while (buffer > start) {                   \
			char tmp = *start;                     \
			*start++ = *buffer;                    \
			*buffer-- = tmp;                       \
		}                                          \
		return buf_end;                            \
	}

XTOA(int, itoa)
XTOA(long int, ltoa)
XTOA(long long int, lltoa)

#define STRTOX(name, type)                                           \
	type name(                                                       \
			const char *restrict s,                                  \
			char **restrict endptr,                                  \
			int radix                                                \
	) {                                                              \
		const char *s_start = s;                                     \
		for (; isspace(*s); s++);                                    \
                                                                     \
		int sign = 0;                                                \
		switch (*s) {                                                \
		case '-': sign = 1; /* fallthrough */                        \
		case '+': s++; break;                                        \
		}                                                            \
                                                                     \
		if (                                                         \
			(radix == 0 || radix == 16)                              \
			&& (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))         \
		) {                                                          \
			radix = 16;                                              \
			s += 2;                                                  \
		} else if (radix == 0) {                                     \
			if (*s == '0') {                                         \
				radix = 8;                                           \
				s++;                                                 \
			} else {                                                 \
				radix = 10;                                          \
			}                                                        \
		}                                                            \
                                                                     \
		type num = 0;                                                \
		int has_digit = 0;                                           \
                                                                     \
		while (1) {                                                  \
			int n = ctoi(*s++);                                      \
			if (n < 0 || n >= radix) break;                          \
			has_digit = 1;                                           \
			num = num * radix + n;                                   \
		}                                                            \
                                                                     \
		if (endptr != NULL) {                                        \
			*endptr = has_digit ? (char *)(s - 1) : (char *)s_start; \
		}                                                            \
		                                                             \
		return sign ? -num : num;                                    \
	}

STRTOX(strtoi, int)
STRTOX(strtol, long int)
STRTOX(strtoll, long long int)

#define STRTOUX(name, type)                                          \
	type name(                                                       \
			const char *restrict s,                                  \
			char **restrict endptr,                                  \
			int radix                                                \
	) {                                                              \
		const char *s_start = s;                                     \
		for (; isspace(*s); s++);                                    \
                                                                     \
		if (                                                         \
			(radix == 0 || radix == 16)                              \
			&& (s[0] == '0' && (s[1] == 'x' || s[1] == 'X'))         \
		) {                                                          \
			radix = 16;                                              \
			s += 2;                                                  \
		} else if (radix == 0) {                                     \
			if (*s == '0') {                                         \
				radix = 8;                                           \
				s++;                                                 \
			} else {                                                 \
				radix = 10;                                          \
			}                                                        \
		}                                                            \
                                                                     \
		type num = 0;                                                \
		int has_digit = 0;                                           \
                                                                     \
		while (1) {                                                  \
			int n = ctoi(*s++);                                      \
			if (n < 0 || n >= radix) break;                          \
			has_digit = 1;                                           \
			num = num * radix + n;                                   \
		}                                                            \
                                                                     \
		if (endptr != NULL) {                                        \
			*endptr = has_digit ? (char *)(s - 1) : (char *)s_start; \
		}                                                            \
		                                                             \
		return num;                                                  \
	}

STRTOUX(strtoui, unsigned int)
STRTOUX(strtoul, unsigned long int)
STRTOUX(strtoull, unsigned long long int)

static char suffixes[] = {'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y', 'R', 'Q'};

char *btoa(size_t bytes, char *buf) {
	// no suffix if under 1K, print up to four digits
	if (bytes < 1024) {
		ultoa(bytes, buf, 10);
		return buf;
	}

	// store one digit of remainder for decimal
	unsigned int remainder;
	// power of 1024
	int power = 0;

	// iterate until remaining bytes fits in three digits
	while (bytes >= 1000) {
		remainder = (bytes % 1024) * 10 / 1024;
		bytes /= 1024;
		power += 1;
	}

	// end of number
	char *end;

	if (bytes >= 10) {
		// no decimal
		end = ultoa(bytes, buf, 10);
	} else {
		// decimal
		end = ultoa(bytes, buf, 10);
		end[0] = '.';
		end = ultoa(remainder, end + 1, 10);
	}

	// add suffix
	end[0] = suffixes[power - 1];
	end[1] = '\0';

	return buf;
}