From b72dc79eec3d369a38202522165f5ef4cfa5b98b Mon Sep 17 00:00:00 2001 From: Jose Antonio Ortega Ruiz Date: Tue, 9 Apr 2019 02:40:05 +0100 Subject: Support IOC commands for disk/drum devices Thanks to Kevin Brunelle There is a minor fix included with regards to tape devices. The test was failing if M == 0, when it should fail when M != 0. NOTICE: This patch changes the behavior of the VM and changes the function parameters for the ioc_ function. Documentation changes are included. Permits the following: LDX BLKNUM IOC 0(8) OUT ADDR(8) Write block from ADDR into disk[BLKNUM] IOC 0(8) IN ADDR(8) Read block from disk[BLKNUM] into ADDR ... BLKNUM CON 45000 Example possible block on disk I was having an issue writing a block to a drive and then reading back the same block. Because it is impossible to move the SEEK_CUR pointer backwards on a disk device, there was no way for a program to read back a block that it wrote to a disk without restarting or fiddling with ~/.mdk/disk?.dev files and symbolic links. I have added a function parameter to the ioc_ function and used it to pass the value of rX to ioc_. This permits us to use IOC commands to move the read/write head on a disk/drum device. I believe that this conforms to the potential meaning of Knuth's description of IOC for disk/drum devices. I have put in tests to verify that rX is positive and M = 0. I have updated the documentation to reflect this new behavior. This makes disks much more usable. Note: I won't be offended if this patch is rejected because it changed the behavior of the VM. I think it fits the spirit and enhances the functionality in a way that some might find useful. I wanted it for something I was working on, and I felt others might want the same. The thing with the paper-tape should be fixed, though. --- mixlib/xmix_vm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mixlib/xmix_vm.c') diff --git a/mixlib/xmix_vm.c b/mixlib/xmix_vm.c index 68a8106..1b8d80a 100644 --- a/mixlib/xmix_vm.c +++ b/mixlib/xmix_vm.c @@ -303,6 +303,7 @@ ioc_handler_ (mix_vm_t *vm, const mix_ins_t *ins) { mix_address_t addr; mix_device_t *dev; + mix_word_t val; g_assert (ins->opcode == mix_opIOC); @@ -312,7 +313,8 @@ ioc_handler_ (mix_vm_t *vm, const mix_ins_t *ins) dev = get_dev_ (vm, ins->fspec); fail_if_not_ (vm, dev != NULL, MIX_VM_ERROR_BAD_DEVICE_NO); - fail_if_not_ (vm, mix_device_ioc (dev, addr), MIX_VM_ERROR_DEV_CTL); + val = get_rX_ (vm); + fail_if_not_ (vm, mix_device_ioc (dev, addr, val), MIX_VM_ERROR_DEV_CTL); inc_loc_ (vm); return TRUE; -- cgit v1.2.3