blending.cpp

Android 一些工具

        ADD(AL, 0, factor.reg, fragment.reg,
            reg_imm(fragment.reg, LSR, fragment.s-1));
        break;
    case GGL_ONE_MINUS_SRC_ALPHA:
    case GGL_SRC_ALPHA:
        factor.s = src_alpha.s;
        ADD(AL, 0, factor.reg, src_alpha.reg,
                reg_imm(src_alpha.reg, LSR, src_alpha.s-1));
        break;
    case GGL_ONE_MINUS_DST_ALPHA:
    case GGL_DST_ALPHA:
        // XXX: should be precomputed
        extract(factor, dst_pixel, GGLFormat::ALPHA);
        ADD(AL, 0, factor.reg, factor.reg,
                reg_imm(factor.reg, LSR, factor.s-1));
        break;
    case GGL_SRC_ALPHA_SATURATE:
        // XXX: should be precomputed
        // XXX: f = min(As, 1-Ad)
        // btw, we're guaranteed that Ad's size is <= 8, because
        // it's extracted from the framebuffer
        break;
    }

    switch(f) {
    case GGL_ONE_MINUS_DST_COLOR:
    case GGL_ONE_MINUS_SRC_COLOR:
    case GGL_ONE_MINUS_DST_ALPHA:
    case GGL_ONE_MINUS_SRC_ALPHA:
        RSB(AL, 0, factor.reg, factor.reg, imm((1<<factor.s)));
    }
    
    // don't need more than 8-bits for the blend factor
    // and this will prevent overflows in the multiplies later
    if (factor.s > 8) {
        MOV(AL, 0, factor.reg, reg_imm(factor.reg, LSR, factor.s-8));
        factor.s = 8;
    }
}

int GGLAssembler::blending_codes(int fs, int fd)
{
    int blending = 0;
    switch(fs) {
    case GGL_ONE:
        blending |= BLEND_SRC;
        break;

    case GGL_ONE_MINUS_DST_COLOR:
    case GGL_DST_COLOR:
        blending |= FACTOR_DST|BLEND_SRC;
        break;
    case GGL_ONE_MINUS_DST_ALPHA:
    case GGL_DST_ALPHA:
        // no need to extract 'component' from the destination
        // for the blend factor, because we need ALPHA only.
        blending |= BLEND_SRC;
        break;

    case GGL_ONE_MINUS_SRC_COLOR:
    case GGL_SRC_COLOR:    
        blending |= FACTOR_SRC|BLEND_SRC;
        break;
    case GGL_ONE_MINUS_SRC_ALPHA:
    case GGL_SRC_ALPHA:
    case GGL_SRC_ALPHA_SATURATE:
        blending |= FACTOR_SRC|BLEND_SRC;
        break;
    }
    switch(fd) {
    case GGL_ONE:
        blending |= BLEND_DST;
        break;

    case GGL_ONE_MINUS_DST_COLOR:
    case GGL_DST_COLOR:
        blending |= FACTOR_DST|BLEND_DST;
        break;
    case GGL_ONE_MINUS_DST_ALPHA:
    case GGL_DST_ALPHA:
        blending |= FACTOR_DST|BLEND_DST;
        break;

    case GGL_ONE_MINUS_SRC_COLOR:
    case GGL_SRC_COLOR:    
        blending |= FACTOR_SRC|BLEND_DST;
        break;
    case GGL_ONE_MINUS_SRC_ALPHA:
    case GGL_SRC_ALPHA:
        // no need to extract 'component' from the source
        // for the blend factor, because we need ALPHA only.
        blending |= BLEND_DST;
        break;
    }
    return blending;
}

// ---------------------------------------------------------------------------

void GGLAssembler::build_blendFOneMinusF(
        component_t& temp,
        const integer_t& factor, 
        const integer_t& fragment,
        const integer_t& fb)
{
    //  R = S*f + D*(1-f) = (S-D)*f + D
    Scratch scratches(registerFile());
    // compute S-D
    integer_t diff(fragment.flags & CORRUPTIBLE ?
            fragment.reg : scratches.obtain(), fb.size(), CORRUPTIBLE);
    const int shift = fragment.size() - fb.size();
    if (shift>0)        RSB(AL, 0, diff.reg, fb.reg, reg_imm(fragment.reg, LSR, shift));
    else if (shift<0)   RSB(AL, 0, diff.reg, fb.reg, reg_imm(fragment.reg, LSL,-shift));
    else                RSB(AL, 0, diff.reg, fb.reg, fragment.reg);
    mul_factor_add(temp, diff, factor, component_t(fb));
}

void GGLAssembler::build_blendOneMinusFF(
        component_t& temp,
        const integer_t& factor, 
        const integer_t& fragment,
        const integer_t& fb)
{
    //  R = S*f + D*(1-f) = (S-D)*f + D
    Scratch scratches(registerFile());
    // compute D-S
    integer_t diff(fb.flags & CORRUPTIBLE ?
            fb.reg : scratches.obtain(), fb.size(), CORRUPTIBLE);
    const int shift = fragment.size() - fb.size();
    if (shift>0)        SUB(AL, 0, diff.reg, fb.reg, reg_imm(fragment.reg, LSR, shift));
    else if (shift<0)   SUB(AL, 0, diff.reg, fb.reg, reg_imm(fragment.reg, LSL,-shift));
    else                SUB(AL, 0, diff.reg, fb.reg, fragment.reg);
    mul_factor_add(temp, diff, factor, component_t(fragment));
}

// ---------------------------------------------------------------------------

void GGLAssembler::mul_factor(  component_t& d,
                                const integer_t& v,
                                const integer_t& f)
{
    int vs = v.size();
    int fs = f.size();
    int ms = vs+fs;

    // XXX: we could have special cases for 1 bit mul

    // all this code below to use the best multiply instruction
    // wrt the parameters size. We take advantage of the fact
    // that the 16-bits multiplies allow a 16-bit shift
    // The trick is that we just make sure that we have at least 8-bits
    // per component (which is enough for a 8 bits display).

    int xy;
    int vshift = 0;
    int fshift = 0;
    int smulw = 0;

    if (vs<16) {
        if (fs<16) {
            xy = xyBB;
        } else if (GGL_BETWEEN(fs, 24, 31)) {
            ms -= 16;
            xy = xyTB;
        } else {
            // eg: 15 * 18  ->  15 * 15
            fshift = fs - 15;
            ms -= fshift;
            xy = xyBB;
        }
    } else if (GGL_BETWEEN(vs, 24, 31)) {
        if (fs<16) {
            ms -= 16;
            xy = xyTB;
        } else if (GGL_BETWEEN(fs, 24, 31)) {
            ms -= 32;
            xy = xyTT;
        } else {
            // eg: 24 * 18  ->  8 * 18
            fshift = fs - 15;
            ms -= 16 + fshift;
            xy = xyTB;
        }
    } else {
        if (fs<16) {
            // eg: 18 * 15  ->  15 * 15
            vshift = vs - 15;
            ms -= vshift;
            xy = xyBB;
        } else if (GGL_BETWEEN(fs, 24, 31)) {
            // eg: 18 * 24  ->  15 * 8
            vshift = vs - 15;
            ms -= 16 + vshift;
            xy = xyBT;
        } else {
            // eg: 18 * 18  ->  (15 * 18)>>16
            fshift = fs - 15;
            ms -= 16 + fshift;
            xy = yB;    //XXX SMULWB
            smulw = 1;
        }
    }

    LOGE_IF(ms>=32, "mul_factor overflow vs=%d, fs=%d", vs, fs);

    int vreg = v.reg;
    int freg = f.reg;
    if (vshift) {
        MOV(AL, 0, d.reg, reg_imm(vreg, LSR, vshift));
        vreg = d.reg;
    }
    if (fshift) {
        MOV(AL, 0, d.reg, reg_imm(vreg, LSR, fshift));
        freg = d.reg;
    }
    if (smulw)  SMULW(AL, xy, d.reg, vreg, freg);
    else        SMUL(AL, xy, d.reg, vreg, freg);


    d.h = ms;
    if (mDithering) {
        d.l = 0; 
    } else {
        d.l = fs; 
        d.flags |= CLEAR_LO;
    }
}

void GGLAssembler::mul_factor_add(  component_t& d,
                                    const integer_t& v,
                                    const integer_t& f,
                                    const component_t& a)
{
    // XXX: we could have special cases for 1 bit mul
    Scratch scratches(registerFile());

    int vs = v.size();
    int fs = f.size();
    int as = a.h;
    int ms = vs+fs;

    LOGE_IF(ms>=32, "mul_factor_add overflow vs=%d, fs=%d, as=%d", vs, fs, as);

    integer_t add(a.reg, a.h, a.flags);

    // 'a' is a component_t but it is guaranteed to have
    // its high bits set to 0. However in the dithering case,
    // we can't get away with truncating the potentially bad bits
    // so extraction is needed.

   if ((mDithering) && (a.size() < ms)) {
        // we need to expand a
        if (!(a.flags & CORRUPTIBLE)) {
            // ... but it's not corruptible, so we need to pick a
            // temporary register.
            // Try to uses the destination register first (it's likely
            // to be usable, unless it aliases an input).
            if (d.reg!=a.reg && d.reg!=v.reg && d.reg!=f.reg) {
                add.reg = d.reg;
            } else {
                add.reg = scratches.obtain();
            }
        }
        expand(add, a, ms); // extracts and expands
        as = ms;
    }

    if (ms == as) {
        if (vs<16 && fs<16) SMLABB(AL, d.reg, v.reg, f.reg, add.reg);
        else                MLA(AL, 0, d.reg, v.reg, f.reg, add.reg);
    } else {
        int temp = d.reg;
        if (temp == add.reg) {
            // the mul will modify add.reg, we need an intermediary reg
            if (v.flags & CORRUPTIBLE)      temp = v.reg;
            else if (f.flags & CORRUPTIBLE) temp = f.reg;
            else                            temp = scratches.obtain();
        }

        if (vs<16 && fs<16) SMULBB(AL, temp, v.reg, f.reg);
        else                MUL(AL, 0, temp, v.reg, f.reg);

        if (ms>as) {
            ADD(AL, 0, d.reg, temp, reg_imm(add.reg, LSL, ms-as));
        } else if (ms<as) {
            // not sure if we should expand the mul instead?
            ADD(AL, 0, d.reg, temp, reg_imm(add.reg, LSR, as-ms));
        }
    }

    d.h = ms;
    if (mDithering) {
        d.l = a.l; 
    } else {
        d.l = fs>a.l ? fs : a.l;
        d.flags |= CLEAR_LO;
    }
}

void GGLAssembler::component_add(component_t& d,
        const integer_t& dst, const integer_t& src)
{
    // here we're guaranteed that fragment.size() >= fb.size()
    const int shift = src.size() - dst.size();
    if (!shift) {
        ADD(AL, 0, d.reg, src.reg, dst.reg);
    } else {
        ADD(AL, 0, d.reg, src.reg, reg_imm(dst.reg, LSL, shift));
    }

    d.h = src.size();
    if (mDithering) {
        d.l = 0;
    } else {
        d.l = shift;
        d.flags |= CLEAR_LO;
    }
}

void GGLAssembler::component_sat(const component_t& v)
{
    const int one = ((1<<v.size())-1)<<v.l;
    CMP(AL, v.reg, imm( 1<<v.h ));
    if (isValidImmediate(one)) {
        MOV(HS, 0, v.reg, imm( one ));
    } else if (isValidImmediate(~one)) {
        MVN(HS, 0, v.reg, imm( ~one ));
    } else {
        MOV(HS, 0, v.reg, imm( 1<<v.h ));
        SUB(HS, 0, v.reg, v.reg, imm( 1<<v.l ));
    }
}

// ----------------------------------------------------------------------------

}; // namespace android