diff --git a/common/drivers/disk.s2.c b/common/drivers/disk.s2.c index 66bb03ef..58d65cd1 100644 --- a/common/drivers/disk.s2.c +++ b/common/drivers/disk.s2.c @@ -42,7 +42,7 @@ struct dap { #define XFER_BUF_SIZE (xfer_sizes[SIZEOF_ARRAY(xfer_sizes) - 1] * 512) static const size_t xfer_sizes[] = { 1, 2, 4, 8, 16, 24, 32, 48, 64 }; -static void *xfer_buf = NULL; +static uint8_t *xfer_buf = NULL; static size_t fastest_xfer_size(struct volume *volume) { struct dap dap = {0}; @@ -125,6 +125,67 @@ int disk_read_sectors(struct volume *volume, void *buf, uint64_t block, size_t c return DISK_SUCCESS; } +static bool detect_sector_size(struct volume *volume) { + struct dap dap = {0}; + + if (xfer_buf == NULL) + xfer_buf = conv_mem_alloc(XFER_BUF_SIZE); + + dap.size = 16; + dap.count = 1; + dap.segment = rm_seg(xfer_buf); + dap.offset = rm_off(xfer_buf); + dap.lba = 0; + + struct rm_regs r = {0}; + r.eax = 0x4200; + r.edx = volume->drive; + r.esi = (uint32_t)rm_off(&dap); + r.ds = rm_seg(&dap); + + struct rm_regs r_copy = r; + struct dap dap_copy = dap; + + memset(xfer_buf, 0, XFER_BUF_SIZE); + + rm_int(0x13, &r, &r); + + if (r.eflags & EFLAGS_CF) { + return false; + } + + size_t sector_size_a = 0; + for (size_t i = XFER_BUF_SIZE - 1; i >= 0; i--) { + if (xfer_buf[i] != 0) { + sector_size_a = i + 1; + break; + } + } + + r = r_copy; + dap = dap_copy; + + memset(xfer_buf, 0xff, XFER_BUF_SIZE); + + rm_int(0x13, &r, &r); + + if (r.eflags & EFLAGS_CF) { + return false; + } + + size_t sector_size_b = 0; + for (size_t i = XFER_BUF_SIZE - 1; i >= 0; i--) { + if (xfer_buf[i] != 0xff) { + sector_size_b = i + 1; + break; + } + } + + volume->sector_size = sector_size_a > sector_size_b ? sector_size_a : sector_size_b; + + return true; +} + void disk_create_index(void) { volume_index = ext_mem_alloc(sizeof(struct volume) * MAX_VOLUMES); @@ -148,21 +209,22 @@ void disk_create_index(void) { rm_int(0x13, &r, &r); - if (r.eflags & EFLAGS_CF) - continue; - - if (drive_params.bytes_per_sect == 0) + if (r.eflags & EFLAGS_CF) { continue; + } struct volume *block = ext_mem_alloc(sizeof(struct volume)); block->drive = drive; block->partition = 0; - block->sector_size = drive_params.bytes_per_sect; block->first_sect = 0; block->sect_count = drive_params.lba_count; block->max_partition = -1; + if (!detect_sector_size(block)) { + continue; + } + if (drive_params.info_flags & (1 << 2) && drive > 0x8f) { // The medium could not be present (e.g.: CD-ROMs) // Do a test run to see if we can actually read it