From ba21b6a9f5ab8d223f646d6d5adc3dfaa06013f0 Mon Sep 17 00:00:00 2001 From: Virgil Dupras Date: Sun, 25 Oct 2020 10:27:52 -0400 Subject: [PATCH] emul/8086: add PC/AT emulator --- emul/8086/.gitignore | 1 + emul/8086/Makefile | 5 +- emul/8086/README.md | 30 ++++++++++-- emul/8086/cpu.c | 4 +- emul/8086/cpu.h | 2 +- emul/8086/forth.c | 2 +- emul/8086/pcat.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++++ recipes/pcat/Makefile | 10 ++-- recipes/pcat/README.md | 8 +++- recipes/pcat/blk/607 | 2 +- 10 files changed, 175 insertions(+), 16 deletions(-) create mode 100644 emul/8086/pcat.c diff --git a/emul/8086/.gitignore b/emul/8086/.gitignore index 00dbdb8..03a12c4 100644 --- a/emul/8086/.gitignore +++ b/emul/8086/.gitignore @@ -1,2 +1,3 @@ /forth /forth.bin +/pcat diff --git a/emul/8086/Makefile b/emul/8086/Makefile index 538c50e..5932159 100644 --- a/emul/8086/Makefile +++ b/emul/8086/Makefile @@ -1,4 +1,4 @@ -TARGETS = forth +TARGETS = forth pcat OBJS = cpu.o CDIR = ../../cvm STAGE = $(CDIR)/stage @@ -13,6 +13,9 @@ forth: forth.c forth.bin $(OBJS) $(BLKFS) forth.bin: xcomp.fs $(STAGE) $(CDIR)/stage < xcomp.fs > $@ +pcat: pcat.c $(OBJS) $(BLKFS) + $(CC) -DBLKFS_PATH=\"`pwd`/$(BLKFS)\" pcat.c $(OBJS) -lncurses -o $@ + $(BLKFS): $(STAGE) $(STAGE): diff --git a/emul/8086/README.md b/emul/8086/README.md index ae2db1c..f4d2413 100644 --- a/emul/8086/README.md +++ b/emul/8086/README.md @@ -1,8 +1,28 @@ # 8086 emulator -This is a work in progress. The goal is to have something lighter than QEMU to -run Collapse OS on and also something that is easier to plug with my stuff. -Something I could run without BIOS (have my own studs for INT 10 and INT 13). +This folder contains emulator for 8086 binaries of Collapse OS. The bulk of +it is a fork of Fake86 by Mike Chambers. -My first try was with 8086tiny, but this code is messy. Fake86 is a bit bigger, -but also cleaner. +`forth` is an imaginary hardware used for userspace development and testing. +This machine has an imaginary interrupt API and does not conform to PC/AT. + +`pcat` is a very simple PC/AT emulator. The BIOS interrupt hooks implemented in +it only cover Collapse OS' own needs. + +## Requirements + +You need `ncurses` to build the `forth` executable. In debian-based distros, +it's `libncurses5-dev`. + +## Build + +Run `make` and it builds the `forth` and `pcat` interpreters. + +## Usage + +The `./forth` executable here works like the one in `/cvm`, except that it runs +under an emulated 8086 machine instead of running natively. Refer to +`/cvm/README.md` for details. + +`pcat` needs to be suppied a path to a floppy disk image with a proper MBR. +`disk.bin` provided by the `pcat` recipe is sufficient. diff --git a/emul/8086/cpu.c b/emul/8086/cpu.c index 8c55681..b427749 100755 --- a/emul/8086/cpu.c +++ b/emul/8086/cpu.c @@ -3399,8 +3399,8 @@ int exec86(int execloops) { return 1; } -void reset86() { +void reset86(uint16_t startip) { segregs[regcs] = 0; - ip = 0; + ip = startip; hltstate = 0; } diff --git a/emul/8086/cpu.h b/emul/8086/cpu.h index 3c0add6..0490c39 100755 --- a/emul/8086/cpu.h +++ b/emul/8086/cpu.h @@ -52,4 +52,4 @@ void writew86 (uint32_t addr32, uint16_t value); uint8_t read86 (uint32_t addr32); uint16_t readw86 (uint32_t addr32); int exec86(int execloops); // returns 0 if halted -void reset86(); +void reset86(uint16_t startip); diff --git a/emul/8086/forth.c b/emul/8086/forth.c index 049b942..a02de1d 100644 --- a/emul/8086/forth.c +++ b/emul/8086/forth.c @@ -93,7 +93,7 @@ int main(int argc, char *argv[]) INTHOOKS[4] = int4; INTHOOKS[5] = int5; INTHOOKS[6] = int6; - reset86(); + reset86(0); fprintf(stderr, "Using blkfs %s\n", BLKFS_PATH); blkfp = fopen(BLKFS_PATH, "r+"); if (!blkfp) { diff --git a/emul/8086/pcat.c b/emul/8086/pcat.c new file mode 100644 index 0000000..a29a577 --- /dev/null +++ b/emul/8086/pcat.c @@ -0,0 +1,127 @@ +#include +#include +#include +#include +#include "cpu.h" + +#define WCOLS 80 +#define WLINES 25 +#define SEC_PER_TRK 0x3f +#define TRK_PER_HEAD 0xff + +extern uint8_t byteregtable[8]; +extern union _bytewordregs_ regs; +extern uint16_t segregs[4]; +extern INTHOOK INTHOOKS[0x100]; + +static FILE *fp; +WINDOW *bw, *dw, *w; + +static void int10() { + uint8_t cmd = regs.byteregs[regah]; + uint8_t al = regs.byteregs[regal]; + uint16_t dx = regs.wordregs[regdx]; + switch (cmd) { + case 0x02: // at-xy + wmove(w, dx&0xff, dx>>8); + break; + case 0x0e: // emit + if (al >= 0x20 || al == '\n') { + wechochar(w, al); + } else if (al == 0x08) { + int y, x; getyx(w, y, x); + wmove(w, y, x-1); + } + break; + } +} + +static void int13() { + uint8_t cmd = regs.byteregs[regah]; + uint8_t al = regs.byteregs[regal]; + uint8_t cl = regs.byteregs[regcl]; + uint8_t ch = regs.byteregs[regch]; + uint8_t dh = regs.byteregs[regdh]; + uint16_t bx = regs.wordregs[regbx]; + switch (cmd) { + case 0x02: // read disk sector(s) + case 0x03: // write disk sector(s) + // CL = sector number (1-based), AL = sector count + // DH = head number, CH = track number + // ES:BX = dest addr + fseek(fp, ((((dh*TRK_PER_HEAD)+ch)*SEC_PER_TRK)+cl-1)*512, SEEK_SET); + for (int i=0; i<(al*512); i++) { + if (cmd == 0x03) { // write + fputc(getmem8(segregs[reges], bx+i), fp); + } else { // read + putmem8(segregs[reges], bx+i, fgetc(fp)); + } + } + break; + + case 0x08: // poll sectors per track / per head + // we just report a lot of them + regs.wordregs[regcx] = SEC_PER_TRK; + regs.byteregs[regdh] = TRK_PER_HEAD-1; + break; + } +} + +static void int16() { + int c; + // debug_panel(); + c = wgetch(w); + regs.byteregs[regal] = c; +} + +static void usage() +{ + fprintf(stderr, "Usage: ./pcat /path/to/fd\n"); +} + +int main(int argc, char *argv[]) +{ + if (argc < 2) { + usage(); + return 1; + } + INTHOOKS[0x10] = int10; + INTHOOKS[0x13] = int13; + INTHOOKS[0x16] = int16; + reset86(0x7c00); + // initialize memory + fp = fopen(argv[1], "r"); + if (!fp) { + fprintf(stderr, "Can't open %s\n", argv[1]); + return 1; + } + // read MBR into RAM + for (int i=0; i<512; i++) { + int c = getc(fp); + if (c != EOF) { + write86(0x7c00+i, c); + } + } + uint16_t magic = readw86(0x7dfe); + if (magic != 0xaa55) { + fprintf(stderr, "Invalid MBR magic %x\n", magic); + return 1; + } + initscr(); cbreak(); noecho(); nl(); clear(); + // border window + bw = newwin(WLINES+2, WCOLS+2, 0, 0); + wborder(bw, 0, 0, 0, 0, 0, 0, 0, 0); + wrefresh(bw); + // debug panel + dw = newwin(1, 30, LINES-1, COLS-30); + w = newwin(WLINES, WCOLS, 1, 1); + scrollok(w, 1); + while (exec86(100)) { + //debug_panel(); + } + nocbreak(); echo(); delwin(w); delwin(bw); delwin(dw); endwin(); + printf("\nDone!\n"); + //emul_printdebug(); + fclose(fp); + return 0; +} diff --git a/recipes/pcat/Makefile b/recipes/pcat/Makefile index 1740ef9..f83e733 100644 --- a/recipes/pcat/Makefile +++ b/recipes/pcat/Makefile @@ -3,6 +3,7 @@ BASE = ../.. CDIR = $(BASE)/cvm BLKPACK = $(BASE)/tools/blkpack STAGE = $(CDIR)/stage +EMUL = $(BASE)/emul/8086/pcat .PHONY: all all: $(TARGET) @@ -10,7 +11,7 @@ os.bin: xcomp.fs $(STAGE) blkfs $(STAGE) blkfs < xcomp.fs > $@ $(BLKPACK): - $(MAKE) -C ../tools + $(MAKE) -C $(BASE)/tools blkfs: $(BLKPACK) $(BLKPACK) $(BASE)/blk blk > $@ @@ -25,9 +26,12 @@ $(TARGET): mbr.bin os.bin cat mbr.bin os.bin > $@ dd if=blkfs of=$@ bs=512 seek=16 +$(EMUL): + $(MAKE) -C $(BASE)/emul/8086 + .PHONY: emul -emul: $(TARGET) - qemu-system-i386 -drive file=$(TARGET),if=floppy,format=raw +emul: $(TARGET) $(EMUL) + $(EMUL) $(TARGET) .PHONY: clean clean: diff --git a/recipes/pcat/README.md b/recipes/pcat/README.md index e924f62..6cd63d3 100644 --- a/recipes/pcat/README.md +++ b/recipes/pcat/README.md @@ -12,7 +12,6 @@ is bootable on a modern PC-compatible machine. * A modern PC-compatible machine that can boot from a USB drive. * A USB drive -* qemu for emulation ## Build the binary @@ -30,7 +29,12 @@ can run `VE`. ## Emulation -You can run the built binary in qemu using `make emul`. +You can run the built binary in Collapse OS' 8086 emulator using `make emul`. + +The 8086 emulator is barbone. If you prefer to use it on a more realistic +setting, use QEMU. The command is: + + qemu-system-i386 -drive file=disk.bin,if=floppy,format=raw ## Running on a modern PC diff --git a/recipes/pcat/blk/607 b/recipes/pcat/blk/607 index c6a117b..2aaac38 100644 --- a/recipes/pcat/blk/607 +++ b/recipes/pcat/blk/607 @@ -2,7 +2,7 @@ ( AH=read sectors, AL=1 sector, BX=dest, CH=trackno CL=secno DH=head DL=drive ) FDSPT C@ /MOD ( AX BX sec trk ) - FDHEADS C@ /MOD ( AX BX sec head trk ) + FDHEADS C@ /MOD SWAP ( AX BX sec head trk ) 8 LSHIFT ROT OR 1+ ( AX BX head CX ) SWAP 8 LSHIFT 0x03 C@ ( boot drive ) OR ( AX BX CX DX ) 13H 2DROP 2DROP