/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _VIDEO_ATAFB_UTILS_H
#define _VIDEO_ATAFB_UTILS_H

/* ================================================================= */
/*                      Utility Assembler Functions                  */
/* ================================================================= */

/* ====================================================================== */

/* Those of a delicate disposition might like to skip the next couple of
 * pages.
 *
 * These functions are drop in replacements for memmove and
 * memset(_, 0, _). However their five instances add at least a kilobyte
 * to the object file. You have been warned.
 *
 * Not a great fan of assembler for the sake of it, but I think
 * that these routines are at least 10 times faster than their C
 * equivalents for large blits, and that's important to the lowest level of
 * a graphics driver. Question is whether some scheme with the blitter
 * would be faster. I suspect not for simple text system - not much
 * asynchrony.
 *
 * Code is very simple, just gruesome expansion. Basic strategy is to
 * increase data moved/cleared at each step to 16 bytes to reduce
 * instruction per data move overhead. movem might be faster still
 * For more than 15 bytes, we try to align the write direction on a
 * longword boundary to get maximum speed. This is even more gruesome.
 * Unaligned read/write used requires 68020+ - think this is a problem?
 *
 * Sorry!
 */


/* ++roman: I've optimized Robert's original versions in some minor
 * aspects, e.g. moveq instead of movel, let gcc choose the registers,
 * use movem in some places...
 * For other modes than 1 plane, lots of more such assembler functions
 * were needed (e.g. the ones using movep or expanding color values).
 */

/* ++andreas: more optimizations:
   subl #65536,d0 replaced by clrw d0; subql #1,d0 for dbcc
   addal is faster than addaw
   movep is rather expensive compared to ordinary move's
   some functions rewritten in C for clarity, no speed loss */

static inline void *fb_memclear_small(void *s, size_t count)
{
        if (!count)
                return 0;

        asm volatile ("\n"
                "       lsr.l   #1,%1 ; jcc 1f ; move.b %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.w %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.l %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.l %2,-(%0) ; move.l %2,-(%0)\n"
                "1:"
                : "=a" (s), "=d" (count)
                : "d" (0), "0" ((char *)s + count), "1" (count));
        asm volatile ("\n"
                "       subq.l  #1,%1\n"
                "       jcs     3f\n"
                "       move.l  %2,%%d4; move.l %2,%%d5; move.l %2,%%d6\n"
                "2:     movem.l %2/%%d4/%%d5/%%d6,-(%0)\n"
                "       dbra    %1,2b\n"
                "3:"
                : "=a" (s), "=d" (count)
                : "d" (0), "0" (s), "1" (count)
                : "d4", "d5", "d6"
                );

        return 0;
}


static inline void *fb_memclear(void *s, size_t count)
{
        if (!count)
                return 0;

        if (count < 16) {
                asm volatile ("\n"
                        "       lsr.l   #1,%1 ; jcc 1f ; clr.b (%0)+\n"
                        "1:     lsr.l   #1,%1 ; jcc 1f ; clr.w (%0)+\n"
                        "1:     lsr.l   #1,%1 ; jcc 1f ; clr.l (%0)+\n"
                        "1:     lsr.l   #1,%1 ; jcc 1f ; clr.l (%0)+ ; clr.l (%0)+\n"
                        "1:"
                        : "=a" (s), "=d" (count)
                        : "0" (s), "1" (count));
        } else {
                long tmp;
                asm volatile ("\n"
                        "       move.l  %1,%2\n"
                        "       lsr.l   #1,%2 ; jcc 1f ; clr.b (%0)+ ; subq.w #1,%1\n"
                        "       lsr.l   #1,%2 ; jcs 2f\n"  /* %0 increased=>bit 2 switched*/
                        "       clr.w   (%0)+  ; subq.w  #2,%1 ; jra 2f\n"
                        "1:     lsr.l   #1,%2 ; jcc 2f\n"
                        "       clr.w   (%0)+  ; subq.w  #2,%1\n"
                        "2:     move.w  %1,%2; lsr.l #2,%1 ; jeq 6f\n"
                        "       lsr.l   #1,%1 ; jcc 3f ; clr.l (%0)+\n"
                        "3:     lsr.l   #1,%1 ; jcc 4f ; clr.l (%0)+ ; clr.l (%0)+\n"
                        "4:     subq.l  #1,%1 ; jcs 6f\n"
                        "5:     clr.l   (%0)+; clr.l (%0)+ ; clr.l (%0)+ ; clr.l (%0)+\n"
                        "       dbra    %1,5b ; clr.w %1; subq.l #1,%1; jcc 5b\n"
                        "6:     move.w  %2,%1; btst #1,%1 ; jeq 7f ; clr.w (%0)+\n"
                        "7:     btst    #0,%1 ; jeq 8f ; clr.b (%0)+\n"
                        "8:"
                        : "=a" (s), "=d" (count), "=d" (tmp)
                        : "0" (s), "1" (count));
        }

        return 0;
}


static inline void *fb_memset255(void *s, size_t count)
{
        if (!count)
                return 0;

        asm volatile ("\n"
                "       lsr.l   #1,%1 ; jcc 1f ; move.b %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.w %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.l %2,-(%0)\n"
                "1:     lsr.l   #1,%1 ; jcc 1f ; move.l %2,-(%0) ; move.l %2,-(%0)\n"
                "1:"
                : "=a" (s), "=d" (count)
                : "d" (-1), "0" ((char *)s+count), "1" (count));
        asm volatile ("\n"
                "       subq.l  #1,%1 ; jcs 3f\n"
                "       move.l  %2,%%d4; move.l %2,%%d5; move.l %2,%%d6\n"
                "2:     movem.l %2/%%d4/%%d5/%%d6,-(%0)\n"
                "       dbra    %1,2b\n"
                "3:"
                : "=a" (s), "=d" (count)
                : "d" (-1), "0" (s), "1" (count)
                : "d4", "d5", "d6");

        return 0;
}


static inline void *fb_memmove(void *d, const void *s, size_t count)
{
        if (d < s) {
                if (count < 16) {
                        asm volatile ("\n"
                                "       lsr.l   #1,%2 ; jcc 1f ; move.b (%1)+,(%0)+\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.w (%1)+,(%0)+\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.l (%1)+,(%0)+\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.l (%1)+,(%0)+ ; move.l (%1)+,(%0)+\n"
                                "1:"
                                : "=a" (d), "=a" (s), "=d" (count)
                                : "0" (d), "1" (s), "2" (count));
                } else {
                        long tmp;
                        asm volatile ("\n"
                                "       move.l  %0,%3\n"
                                "       lsr.l   #1,%3 ; jcc 1f ; move.b (%1)+,(%0)+ ; subqw #1,%2\n"
                                "       lsr.l   #1,%3 ; jcs 2f\n"  /* %0 increased=>bit 2 switched*/
                                "       move.w  (%1)+,(%0)+  ; subqw  #2,%2 ; jra 2f\n"
                                "1:     lsr.l   #1,%3 ; jcc 2f\n"
                                "       move.w  (%1)+,(%0)+  ; subqw  #2,%2\n"
                                "2:     move.w  %2,%-; lsr.l #2,%2 ; jeq 6f\n"
                                "       lsr.l   #1,%2 ; jcc 3f ; move.l (%1)+,(%0)+\n"
                                "3:     lsr.l   #1,%2 ; jcc 4f ; move.l (%1)+,(%0)+ ; move.l (%1)+,(%0)+\n"
                                "4:     subq.l  #1,%2 ; jcs 6f\n"
                                "5:     move.l  (%1)+,(%0)+; move.l (%1)+,(%0)+\n"
                                "       move.l  (%1)+,(%0)+; move.l (%1)+,(%0)+\n"
                                "       dbra    %2,5b ; clr.w %2; subq.l #1,%2; jcc 5b\n"
                                "6:     move.w  %+,%2; btst #1,%2 ; jeq 7f ; move.w (%1)+,(%0)+\n"
                                "7:     btst    #0,%2 ; jeq 8f ; move.b (%1)+,(%0)+\n"
                                "8:"
                                : "=a" (d), "=a" (s), "=d" (count), "=d" (tmp)
                                : "0" (d), "1" (s), "2" (count));
                }
        } else {
                if (count < 16) {
                        asm volatile ("\n"
                                "       lsr.l   #1,%2 ; jcc 1f ; move.b -(%1),-(%0)\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.w -(%1),-(%0)\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.l -(%1),-(%0)\n"
                                "1:     lsr.l   #1,%2 ; jcc 1f ; move.l -(%1),-(%0) ; move.l -(%1),-(%0)\n"
                                "1:"
                                : "=a" (d), "=a" (s), "=d" (count)
                                : "0" ((char *) d + count), "1" ((char *) s + count), "2" (count));
                } else {
                        long tmp;

                        asm volatile ("\n"
                                "       move.l  %0,%3\n"
                                "       lsr.l   #1,%3 ; jcc 1f ; move.b -(%1),-(%0) ; subqw #1,%2\n"
                                "       lsr.l   #1,%3 ; jcs 2f\n"  /* %0 increased=>bit 2 switched*/
                                "       move.w  -(%1),-(%0) ; subqw  #2,%2 ; jra 2f\n"
                                "1:     lsr.l   #1,%3 ; jcc 2f\n"
                                "       move.w  -(%1),-(%0) ; subqw  #2,%2\n"
                                "2:     move.w  %2,%-; lsr.l #2,%2 ; jeq 6f\n"
                                "       lsr.l   #1,%2 ; jcc 3f ; move.l -(%1),-(%0)\n"
                                "3:     lsr.l   #1,%2 ; jcc 4f ; move.l -(%1),-(%0) ; move.l -(%1),-(%0)\n"
                                "4:     subq.l  #1,%2 ; jcs 6f\n"
                                "5:     move.l  -(%1),-(%0); move.l -(%1),-(%0)\n"
                                "       move.l  -(%1),-(%0); move.l -(%1),-(%0)\n"
                                "       dbra    %2,5b ; clr.w %2; subq.l #1,%2; jcc 5b\n"
                                "6:     move.w  %+,%2; btst #1,%2 ; jeq 7f ; move.w -(%1),-(%0)\n"
                                "7:     btst    #0,%2 ; jeq 8f ; move.b -(%1),-(%0)\n"
                                "8:"
                                : "=a" (d), "=a" (s), "=d" (count), "=d" (tmp)
                                : "0" ((char *) d + count), "1" ((char *) s + count), "2" (count));
                }
        }

        return 0;
}


/* ++andreas: Simple and fast version of memmove, assumes size is
   divisible by 16, suitable for moving the whole screen bitplane */
static inline void fast_memmove(char *dst, const char *src, size_t size)
{
        if (!size)
                return;
        if (dst < src)
                asm volatile ("\n"
                        "1:     movem.l (%0)+,%%d0/%%d1/%%a0/%%a1\n"
                        "       movem.l %%d0/%%d1/%%a0/%%a1,%1@\n"
                        "       addq.l  #8,%1; addq.l #8,%1\n"
                        "       dbra    %2,1b\n"
                        "       clr.w   %2; subq.l #1,%2\n"
                        "       jcc     1b"
                        : "=a" (src), "=a" (dst), "=d" (size)
                        : "0" (src), "1" (dst), "2" (size / 16 - 1)
                        : "d0", "d1", "a0", "a1", "memory");
        else
                asm volatile ("\n"
                        "1:     subq.l  #8,%0; subq.l #8,%0\n"
                        "       movem.l %0@,%%d0/%%d1/%%a0/%%a1\n"
                        "       movem.l %%d0/%%d1/%%a0/%%a1,-(%1)\n"
                        "       dbra    %2,1b\n"
                        "       clr.w   %2; subq.l #1,%2\n"
                        "       jcc 1b"
                        : "=a" (src), "=a" (dst), "=d" (size)
                        : "0" (src + size), "1" (dst + size), "2" (size / 16 - 1)
                        : "d0", "d1", "a0", "a1", "memory");
}

#ifdef BPL

/*
 * This expands a up to 8 bit color into two longs
 * for movel operations.
 */
static const u32 four2long[] = {
        0x00000000, 0x000000ff, 0x0000ff00, 0x0000ffff,
        0x00ff0000, 0x00ff00ff, 0x00ffff00, 0x00ffffff,
        0xff000000, 0xff0000ff, 0xff00ff00, 0xff00ffff,
        0xffff0000, 0xffff00ff, 0xffffff00, 0xffffffff,
};

static inline void expand8_col2mask(u8 c, u32 m[])
{
        m[0] = four2long[c & 15];
#if BPL > 4
        m[1] = four2long[c >> 4];
#endif
}

static inline void expand8_2col2mask(u8 fg, u8 bg, u32 fgm[], u32 bgm[])
{
        fgm[0] = four2long[fg & 15] ^ (bgm[0] = four2long[bg & 15]);
#if BPL > 4
        fgm[1] = four2long[fg >> 4] ^ (bgm[1] = four2long[bg >> 4]);
#endif
}

/*
 * set an 8bit value to a color
 */
static inline void fill8_col(u8 *dst, u32 m[])
{
        u32 tmp = m[0];
        dst[0] = tmp;
        dst[2] = (tmp >>= 8);
#if BPL > 2
        dst[4] = (tmp >>= 8);
        dst[6] = tmp >> 8;
#endif
#if BPL > 4
        tmp = m[1];
        dst[8] = tmp;
        dst[10] = (tmp >>= 8);
        dst[12] = (tmp >>= 8);
        dst[14] = tmp >> 8;
#endif
}

/*
 * set an 8bit value according to foreground/background color
 */
static inline void fill8_2col(u8 *dst, u8 fg, u8 bg, u32 mask)
{
        u32 fgm[2], bgm[2], tmp;

        expand8_2col2mask(fg, bg, fgm, bgm);

        mask |= mask << 8;
#if BPL > 2
        mask |= mask << 16;
#endif
        tmp = (mask & fgm[0]) ^ bgm[0];
        dst[0] = tmp;
        dst[2] = (tmp >>= 8);
#if BPL > 2
        dst[4] = (tmp >>= 8);
        dst[6] = tmp >> 8;
#endif
#if BPL > 4
        tmp = (mask & fgm[1]) ^ bgm[1];
        dst[8] = tmp;
        dst[10] = (tmp >>= 8);
        dst[12] = (tmp >>= 8);
        dst[14] = tmp >> 8;
#endif
}

static const u32 two2word[] = {
        0x00000000, 0xffff0000, 0x0000ffff, 0xffffffff
};

static inline void expand16_col2mask(u8 c, u32 m[])
{
        m[0] = two2word[c & 3];
#if BPL > 2
        m[1] = two2word[(c >> 2) & 3];
#endif
#if BPL > 4
        m[2] = two2word[(c >> 4) & 3];
        m[3] = two2word[c >> 6];
#endif
}

static inline void expand16_2col2mask(u8 fg, u8 bg, u32 fgm[], u32 bgm[])
{
        bgm[0] = two2word[bg & 3];
        fgm[0] = two2word[fg & 3] ^ bgm[0];
#if BPL > 2
        bgm[1] = two2word[(bg >> 2) & 3];
        fgm[1] = two2word[(fg >> 2) & 3] ^ bgm[1];
#endif
#if BPL > 4
        bgm[2] = two2word[(bg >> 4) & 3];
        fgm[2] = two2word[(fg >> 4) & 3] ^ bgm[2];
        bgm[3] = two2word[bg >> 6];
        fgm[3] = two2word[fg >> 6] ^ bgm[3];
#endif
}

static inline u32 *fill16_col(u32 *dst, int rows, u32 m[])
{
        while (rows) {
                *dst++ = m[0];
#if BPL > 2
                *dst++ = m[1];
#endif
#if BPL > 4
                *dst++ = m[2];
                *dst++ = m[3];
#endif
                rows--;
        }
        return dst;
}

static inline void memmove32_col(void *dst, void *src, u32 mask, u32 h, u32 bytes)
{
        u32 *s, *d, v;

        s = src;
        d = dst;
        do {
                v = (*s++ & mask) | (*d  & ~mask);
                *d++ = v;
#if BPL > 2
                v = (*s++ & mask) | (*d  & ~mask);
                *d++ = v;
#endif
#if BPL > 4
                v = (*s++ & mask) | (*d  & ~mask);
                *d++ = v;
                v = (*s++ & mask) | (*d  & ~mask);
                *d++ = v;
#endif
                d = (u32 *)((u8 *)d + bytes);
                s = (u32 *)((u8 *)s + bytes);
        } while (--h);
}

#endif

#endif /* _VIDEO_ATAFB_UTILS_H */