io_read16
hper = io_read16(sd, REG_H_PER);
hsper = io_read16(sd, REG_HS_WIDTH);
htot = io_read16(sd, REG_FMT_H_TOT);
hact = io_read16(sd, REG_FMT_H_ACT);
hfront = io_read16(sd, REG_FMT_H_FRONT);
hsync = io_read16(sd, REG_FMT_H_SYNC);
hback = io_read16(sd, REG_FMT_H_BACK);
vtot = io_read16(sd, REG_FMT_V_TOT);
vact = io_read16(sd, REG_FMT_V_ACT);
hper = io_read16(sd, REG_H_PER) & MASK_HPER;
hsper = io_read16(sd, REG_HS_WIDTH) & MASK_HSWIDTH;