pxl8/src/pxl8_blit.c

#include "pxl8_blit.h"
#include "pxl8_simd.h"

void pxl8_blit_simd_hicolor(u32* fb, u32 fb_width, const u32* sprite, u32 atlas_width,
                            i32 x, i32 y, u32 w, u32 h) {
    u32* dest_base = fb + y * fb_width + x;
    const u32* src_base = sprite;
    
    for (u32 row = 0; row < h; row++) {
        u32* dest_row = dest_base + row * fb_width;
        const u32* src_row = src_base + row * atlas_width;
        
        u32 col = 0;
        for (; col + PXL8_SIMD_WIDTH_U32 <= w; col += PXL8_SIMD_WIDTH_U32) {
            pxl8_simd_vec src_vec = pxl8_simd_load_u32(src_row + col);
            pxl8_simd_vec dest_vec = pxl8_simd_load_u32(dest_row + col);
            pxl8_simd_vec alpha_mask = pxl8_simd_alpha_mask_u32();
            pxl8_simd_vec has_alpha = pxl8_simd_and(src_vec, alpha_mask);
            pxl8_simd_vec zero = pxl8_simd_zero_u8();
            pxl8_simd_vec mask = pxl8_simd_cmpeq_u32(has_alpha, zero);
            pxl8_simd_vec result = pxl8_simd_blendv_u32(src_vec, dest_vec, mask);
            pxl8_simd_store_u32(dest_row + col, result);
        }
        
        for (; col < w; col++) {
            if (src_row[col] & 0xFF000000) {
                dest_row[col] = src_row[col];
            }
        }
    }
}

void pxl8_blit_simd_indexed(u8* fb, u32 fb_width, const u8* sprite, u32 atlas_width,
                            i32 x, i32 y, u32 w, u32 h) {
    u8* dest_base = fb + y * fb_width + x;
    const u8* src_base = sprite;
    
    for (u32 row = 0; row < h; row++) {
        u8* dest_row = dest_base + row * fb_width;
        const u8* src_row = src_base + row * atlas_width;
        
        u32 col = 0;
        for (; col + PXL8_SIMD_WIDTH_U8 <= w; col += PXL8_SIMD_WIDTH_U8) {
            pxl8_simd_vec src_vec = pxl8_simd_load_u8(src_row + col);
            pxl8_simd_vec dest_vec = pxl8_simd_load_u8(dest_row + col);
            pxl8_simd_vec zero = pxl8_simd_zero_u8();
            pxl8_simd_vec mask = pxl8_simd_cmpeq_u8(src_vec, zero);
            pxl8_simd_vec result = pxl8_simd_blendv_u8(src_vec, dest_vec, mask);
            pxl8_simd_store_u8(dest_row + col, result);
        }
        
        for (; col < w; col++) {
            if (src_row[col] != 0) {
                dest_row[col] = src_row[col];
            }
        }
    }
}