graph_vram.c

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#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;
 
        // 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;
 
}