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/*
* VBMouse - small inline utilities
* Copyright (C) 2022 Javier S. Pedro
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef UTILS_H
#define UTILS_H
#include <stdint.h>
#include <i86.h>
#define STATIC_ASSERT(expr) typedef int STATIC_ASSERT_FAILED[(expr) ? 1 : -1]
#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 __segment get_cs(void);
#pragma aux get_cs = "mov ax, cs" value [ax] modify exact [];
static inline __segment get_ds(void);
#pragma aux get_ds = "mov ax, ds" value [ax] modify exact [];
/** Converts a far pointer into equivalent linear address.
* Note that under protected mode linear != physical (for that, need VDS). */
static inline uint32_t linear_addr(const void __far * ptr)
{
return ((uint32_t)(FP_SEG(ptr)) << 4) + FP_OFF(ptr);
}
/** 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 dx]
/** Map x linearly from range [0, srcmax] to [0, dstmax].
* Equivalent of (x * dstmax) / srcmax but with 32-bit signed precision. */
static int scalei(int x, int srcmax, int dstmax);
#pragma aux scalei = \
"imul cx" /* dx:ax = x * dstmax */ \
"idiv bx" /* ax = dx:ax / srcmax */ \
__parm [ax] [bx] [cx] \
__value [ax] \
__modify [ax 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 */ \
"mov cx, [si]" /* cx = rem */ \
"test cx, cx" \
"setns cl" /* cl = 1 if rem positive, 0 if negative */ \
"movzx cx, cl" \
"dec cx" /* cx = 0 if rem positive, -1 if negative */ \
"add ax, [si]" /* ax += *rem */ \
"adc dx, cx" /* dx += 1 if carry and rem positive, 0 if carry and rem negative (aka. signed addition) */ \
"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 si]
#endif
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