emul/trs80: implement floppy emulation

So far, only the first 400 sectors of the disk image are accessible.

TODO: add keybindings to swap floppies on the emulated machine.

arch/z80/trs80/Makefile

@@ -25,4 +25,4 @@ $(EMUL):
 
 .PHONY: emul
 emul: $(EMUL) $(TARGET)
-	$(EMUL) $(TARGET)
+	$(EMUL) -f blkfs $(TARGET)

emul/z80/Makefile

@@ -13,7 +13,7 @@ BLKFS = $(CDIR)/blkfs
 all: $(TARGETS)
 
 forth: forth.c $(OBJS) $(BLKFS)
-	$(CC) forth.c $(OBJS) -lcurses -o $@
+	$(CC) -DFBIN_PATH=\"`pwd`/forth.bin\" -DBLKFS_PATH=\"`pwd`/$(BLKFS)\" forth.c $(OBJS) -lcurses -o $@
 
 rc2014: rc2014.c $(RC2014_OBJS)
 	$(CC) rc2014.c $(RC2014_OBJS) -o $@
@@ -28,7 +28,7 @@ trs80: trs80.c $(TRS80_OBJS)
 	$(CC) trs80.c $(TRS80_OBJS) -lcurses -o $@
 
 emul.o: emul.c forth.bin $(BLKFS)
-	$(CC) -DFBIN_PATH=\"`pwd`/forth.bin\" -DBLKFS_PATH=\"`pwd`/$(BLKFS)\" -c -o emul.o emul.c
+	$(CC) -c -o emul.o emul.c
 
 forth.bin: xcomp.fs $(STAGE) $(BLKFS)
 	$(CDIR)/stage < xcomp.fs > $@

emul/z80/emul.c

@@ -1,29 +1,11 @@
-/* Common code between forth and stage binaries.
-
-They all run on the same kind of virtual machine: A z80 CPU, 64K of RAM/ROM.
+/* Common code between all z80 emulators
 */
 
 #include <string.h>
 #include "emul.h"
-// Port for block reads. Each read or write has to be done in 5 IO writes:
-// 1 - r/w. 1 for read, 2 for write.
-// 2 - blkid MSB
-// 3 - blkid LSB
-// 4 - dest addr MSB
-// 5 - dest addr LSB
-#define BLK_PORT 0x03
-
-#ifndef BLKFS_PATH
-#error BLKFS_PATH needed
-#endif
-#ifndef FBIN_PATH
-#error FBIN_PATH needed
-#endif
 
 static Machine m;
 static ushort traceval = 0;
-static uint64_t blkop = 0; // 5 bytes
-static FILE *blkfp;
 
 static uint8_t io_read(int unused, uint16_t addr)
 {
@@ -48,24 +30,6 @@ static void io_write(int unused, uint16_t addr, uint8_t val)
     }
 }
 
-static void iowr_blk(uint8_t val)
-{
-    blkop <<= 8;
-    blkop |= val;
-    uint8_t rw = blkop >> 32;
-    if (rw) {
-        uint16_t blkid = (blkop >> 16);
-        uint16_t dest = blkop & 0xffff;
-        blkop = 0;
-        fseek(blkfp, blkid*1024, SEEK_SET);
-        if (rw==2) { // write
-            fwrite(&m.mem[dest], 1024, 1, blkfp);
-        } else { // read
-            fread(&m.mem[dest], 1024, 1, blkfp);
-        }
-    }
-}
-
 static uint8_t mem_read(int unused, uint16_t addr)
 {
     return m.mem[addr];
@@ -84,24 +48,8 @@ static void mem_write(int unused, uint16_t addr, uint8_t val)
 
 Machine* emul_init(char *binpath, ushort binoffset)
 {
-    fprintf(stderr, "Using blkfs %s\n", BLKFS_PATH);
-    blkfp = fopen(BLKFS_PATH, "r+");
-    if (!blkfp) {
-        fprintf(stderr, "Can't open\n");
-        return NULL;
-    }
-    fseek(blkfp, 0, SEEK_END);
-    if (ftell(blkfp) < 100 * 1024) {
-        fclose(blkfp);
-        fprintf(stderr, "emul/blkfs too small, something's wrong, aborting.\n");
-        return NULL;
-    }
-    fseek(blkfp, 0, SEEK_SET);
     // initialize memory
     memset(m.mem, 0, 0x10000);
-    if (binpath == NULL) {
-        binpath = FBIN_PATH;
-    }
     FILE *bfp = fopen(binpath, "r");
     if (!bfp) {
         fprintf(stderr, "Can't open %s\n", binpath);
@@ -134,15 +82,9 @@ Machine* emul_init(char *binpath, ushort binoffset)
     m.cpu.memWrite = mem_write;
     m.cpu.ioRead = io_read;
     m.cpu.ioWrite = io_write;
-    m.iowr[BLK_PORT] = iowr_blk;
     return &m;
 }
 
-void emul_deinit()
-{
-    fclose(blkfp);
-}
-
 bool emul_step()
 {
     if (!m.cpu.halted) {

emul/z80/emul.h

@@ -37,7 +37,6 @@ typedef enum {
 } Tristate;
 
 Machine* emul_init(char *binpath, ushort binoffset);
-void emul_deinit();
 bool emul_step();
 bool emul_steps(unsigned int steps);
 void emul_loop();

emul/z80/forth.c

@@ -13,12 +13,22 @@
 // This binary is also used for automated tests and those tests, when
 // failing, send a non-zero value to RET_PORT to indicate failure
 #define RET_PORT 0x01
+// Port for block reads. Each read or write has to be done in 5 IO writes:
+// 1 - r/w. 1 for read, 2 for write.
+// 2 - blkid MSB
+// 3 - blkid LSB
+// 4 - dest addr MSB
+// 5 - dest addr LSB
+#define BLK_PORT 0x03
 #define SETX_PORT 0x05
 #define SETY_PORT 0x06
 
+static Machine *m;
 static FILE *fp;
 static int retcode = 0;
 WINDOW *bw, *dw, *w;
+static uint64_t blkop = 0; // 5 bytes
+static FILE *blkfp;
 
 void debug_panel()
 {
@@ -57,6 +67,24 @@ static void iowr_stdio(uint8_t val)
     }
 }
 
+static void iowr_blk(uint8_t val)
+{
+    blkop <<= 8;
+    blkop |= val;
+    uint8_t rw = blkop >> 32;
+    if (rw) {
+        uint16_t blkid = (blkop >> 16);
+        uint16_t dest = blkop & 0xffff;
+        blkop = 0;
+        fseek(blkfp, blkid*1024, SEEK_SET);
+        if (rw==2) { // write
+            fwrite(&m->mem[dest], 1024, 1, blkfp);
+        } else { // read
+            fread(&m->mem[dest], 1024, 1, blkfp);
+        }
+    }
+}
+
 static void iowr_ret(uint8_t val)
 {
     retcode = val;
@@ -76,7 +104,20 @@ static void iowr_sety(uint8_t val)
 
 int main(int argc, char *argv[])
 {
-    Machine *m = emul_init(NULL, 0);
+    fprintf(stderr, "Using blkfs %s\n", BLKFS_PATH);
+    blkfp = fopen(BLKFS_PATH, "r+");
+    if (!blkfp) {
+        fprintf(stderr, "Can't open\n");
+        return 1;
+    }
+    fseek(blkfp, 0, SEEK_END);
+    if (ftell(blkfp) < 100 * 1024) {
+        fclose(blkfp);
+        fprintf(stderr, "emul/blkfs too small, something's wrong, aborting.\n");
+        return 1;
+    }
+    fseek(blkfp, 0, SEEK_SET);
+    m = emul_init(FBIN_PATH, 0);
     if (m == NULL) {
         return 1;
     }
@@ -84,6 +125,7 @@ int main(int argc, char *argv[])
     m->iord[STDIO_PORT] = iord_stdio;
     m->iowr[STDIO_PORT] = iowr_stdio;
     m->iowr[RET_PORT] = iowr_ret;
+    m->iowr[BLK_PORT] = iowr_blk;
     m->iowr[SETX_PORT] = iowr_setx;
     m->iowr[SETY_PORT] = iowr_sety;
     w = NULL;
@@ -116,6 +158,6 @@ int main(int argc, char *argv[])
         fprintf(stderr, "Usage: ./forth [filename]\n");
         retcode = 1;
     }
-    emul_deinit();
+    fclose(blkfp);
     return retcode;
 }

emul/z80/trs80.c

@@ -11,6 +11,7 @@
 #define BINSTART 0x3000
 
 WINDOW *bw, *dw, *w;
+static FILE *blkfp = NULL;
 
 void debug_panel()
 {
@@ -40,22 +41,36 @@ static void pchookfunc(Machine *m)
             wmove(w, y, x-1);
         }
         break;
-    case 0x03: // @GET
-        break;
-    case 0x04: // @PUT
-        break;
     case 0x0f: // @VDCTL
         wmove(w, m->cpu.R1.br.H, m->cpu.R1.br.L);
         break;
     case 0x16: // @EXIT
-        break;
-    case 0x1a: // @ERROR
+        m->cpu.halted = true;
         break;
     case 0x28: // @DCSTAT
+        // set Z to indicate floppy presence
+        if (blkfp != NULL) {
+            m->cpu.R1.br.F |= F_Z;
+        } else {
+            m->cpu.R1.br.F &= ~F_Z;
+        }
         break;
+    // 0x100b per sector. 10 sector per cylinder, 40 cylinders per floppy.
+    // TODO: support swapping floppies. only 1 floppy for now.
     case 0x31: // @RDSEC
-        break;
     case 0x35: // @WRSEC
+        if (blkfp != NULL) {
+            fseek(
+                blkfp, /* D = cylinder, E = sector */
+                ((m->cpu.R1.br.D * 10) + m->cpu.R1.br.E) * 0x100,
+                SEEK_SET);
+            if (m->cpu.R1.br.A == 0x31) { // @RDSEC
+                fread(&m->mem[m->cpu.R1.wr.HL], 0x100, 1, blkfp);
+            } else {
+                fwrite(&m->mem[m->cpu.R1.wr.HL], 0x100, 1, blkfp);
+            }
+            m->cpu.R1.br.F |= F_Z;
+        }
         break;
     default:
         fprintf(stderr, "Unhandled RST28: %x\n", m->cpu.R1.br.A);
@@ -64,7 +79,7 @@ static void pchookfunc(Machine *m)
 
 static void usage()
 {
-    fprintf(stderr, "Usage: ./trs80 /path/to/rom\n");
+    fprintf(stderr, "Usage: ./trs80 [-f floppies.img] /path/to/rom\n");
 }
 
 int main(int argc, char *argv[])
@@ -73,7 +88,24 @@ int main(int argc, char *argv[])
         usage();
         return 1;
     }
-    Machine *m = emul_init(argv[1], BINSTART);
+    int ch;
+    while ((ch = getopt(argc, argv, "f:")) != -1) {
+        switch (ch) {
+            case 'f':
+                fprintf(stderr, "Setting up floppies image with %s\n", optarg);
+                blkfp = fopen(optarg, "r+");
+                if (blkfp == NULL) {
+                    fprintf(stderr, "Can't open file\n");
+                    return 1;
+                }
+                break;
+        }
+    }
+    if (optind != argc-1) {
+        usage();
+        return 1;
+    }
+    Machine *m = emul_init(argv[optind], BINSTART);
     if (m == NULL) return 1;
     m->ramstart = RAMSTART;
     m->pchookfunc = pchookfunc;
@@ -98,6 +130,5 @@ int main(int argc, char *argv[])
     printf("\nDone!\n");
     emul_printdebug();
     printf("PC: %x\n", m->cpu.PC);
-    emul_deinit();
     return 0;
 }