#ifndef UTILS_H
#define UTILS_H

#include <stdint.h>

#define ABS(x) (((x) < 0) ? -(x) : (x))

#define MIN(a,b)  (((a) < (b)) ? (a) : (b))
#define MAX(a,b)  (((a) > (b)) ? (a) : (b))

#define BOUND(x,a,b) ( MIN(b, MAX(a, x)) )

static inline void breakpoint(void);
#pragma aux breakpoint = 0xcd 0x03;

static inline void cli(void);
#pragma aux cli = "cli"

static inline void sti(void);
#pragma aux sti = "sti"

/** Map x linearly from range [0, srcmax] to [0, dstmax].
 *  Equivalent of (x * dstmax) / srcmax but with 32-bit unsigned precision. */
static unsigned scaleu(unsigned x, unsigned srcmax, unsigned dstmax);
#pragma aux scaleu = \
	"mul cx" /* dx:ax = x * dstmax */\
	"div bx" /* ax = dx:ax / srcmax */\
	__parm [ax] [bx] [cx] \
	__value [ax] \
	__modify [ax cx dx]

/** Map x linearly from range [0, srcmax] to [0, dstmax].
 *  Equivalent of (x * dstmax) / srcmax but with 32-bit signed precision.
 *  Division remainder is returned in rem, which should be reused
 *  in future calls to reduce rounding error. */
static int scalei_rem(int x, int srcmax, int dstmax, short *rem);
#pragma aux scalei_rem = \
	"imul cx"       /* dx:ax = x * dstmax */ \
	"add ax, [si]"  /* ax += *rem */ \
	"adc dx, 0"     /* dx += 1 if carry */ \
	"idiv bx"       /* ax = dx:ax / srcmax, dx = new remainder */ \
	"mov [si], dx"  /* store the new remainder */ \
	__parm [ax] [bx] [cx] [si] \
	__value [ax] \
	__modify [ax cx dx]

static void bzero(void __far *buf, unsigned int size);
#pragma aux bzero = \
	"cld" \
	"mov ax, 0" \
	"rep stos byte ptr es:[di]" \
	__parm [es di] [cx] \
	__modify [ax]

static void nfmemcpy(void __far *dst, const void *src, unsigned int size);
#pragma aux nfmemcpy = \
	"cld" \
	"rep movs byte ptr es:[di], byte ptr ds:[si]" \
	__parm [es di] [si] [cx] \
	__modify [cx si di]

static void fnmemcpy(void *dst, const void __far *src, unsigned int size);
#pragma aux fnmemcpy = \
	"cld" \
	"push gs" \
	"mov ax, es" \
	"mov gs, ax" /* gs is now the src segment */ \
	"mov ax, ds" \
	"mov es, ax" /* es is now ds, the dst segment */ \
	"rep movs byte ptr es:[di], byte ptr gs:[si]" \
	"pop gs" \
	__parm [di] [es si] [cx] \
	__modify [ax cx si di es]

static void ffmemcpy(void __far *dst, const void __far *src, unsigned int size);
#pragma aux ffmemcpy = \
	"cld" \
	"push gs" \
	"mov gs, ax" \
	"rep movs byte ptr es:[di], byte ptr gs:[si]" \
	"pop gs" \
	__parm [es di] [gs si] [cx] \
	__modify [cx si di]

static void nnmemcpy(void *dst, const void *src, unsigned int size);
#pragma aux nnmemcpy = \
	"cld" \
	"mov ax, ds" \
	"mov es, ax" /* es is now ds, the src+dst segment */ \
	"rep movs byte ptr es:[di], byte ptr ds:[si]" \
	__parm [di] [si] [cx] \
	__modify [cx si di es]

#endif