graph_vram.c

#include <gs_psm.h>
 
#include <graph_vram.h>
 
static int graph_vram_pointer = 0;
 
int graph_vram_allocate(int width, int height, int psm, int alignment)
{
 
    int size;
 
    // Calculate the size and increment the pointer
    size = graph_vram_size(width,height,psm,alignment);
 
    graph_vram_pointer += size;
 
    // Align the pointer
    graph_vram_pointer = -alignment & (graph_vram_pointer + (alignment-1));
 
    // If the pointer overflows the vram size
    if (graph_vram_pointer > GRAPH_VRAM_MAX_WORDS)
    {
 
        graph_vram_pointer -= size;
        return -1;
 
    }
 
    return graph_vram_pointer - size;
 
}
 
void graph_vram_free(int address)
{
 
    graph_vram_pointer = address;
 
}
 
void graph_vram_clear(void)
{
 
    graph_vram_pointer = 0;
 
}
 
int graph_vram_size(int width, int height, int psm, int alignment)
{
 
    int size = 0;
 
    // First correct the buffer width to be a multiple of 64 or 128
    // If the width is less than or equal to 16, then it's a palette
    if (width > 16)
    {
        switch (psm)
        {
 
            case GS_PSM_8:
            case GS_PSM_4:
            case GS_PSM_8H:
            case GS_PSM_4HL:
            case GS_PSM_4HH:    width = -128 & (width + 127); break;
            default:            width = -64  & (width + 63);  break;
 
        }
    }
 
    // Texture storage size is in pixels/word
    switch (psm)
    {
 
        case GS_PSM_4:      size = width*(height>>3); break;
        case GS_PSM_8:      size = width*(height>>2); break;
        case GS_PSM_24:
        case GS_PSM_32:
        case GS_PSM_8H:
        case GS_PSM_4HL:
        case GS_PSM_4HH:
        case GS_PSMZ_24:
        case GS_PSMZ_32:    size = width*height; break;
        case GS_PSM_16:
        case GS_PSM_16S:
        case GS_PSMZ_16:
        case GS_PSMZ_16S:   size = width*(height>>1); break;
        default: return 0;
 
    }
 
    // The buffer size is dependent on alignment
    size = -alignment & (size + (alignment-1));
 
    return size;
 
}