Refactor parallel comms a bit

Makefile

@@ -31,11 +31,13 @@ fat12boot.elf: LDFLAGS += -T bootsect.ld
 
 fat12boot.bin: fat12boot.elf
 
+stdlib.o: CFLAGS := $(filter-out -flto, $(CFLAGS))
+
 polmon.elf: LDFLAGS += -T flat1000.ld
 polmon.elf: polmon.o stdlib.o
 
 polio.elf: LDFLAGS += -T flat0600.ld
-polio.elf: polio-main.o polio.s fat12.o paracomm.o
+polio.elf: polio-main.o polio.s fat12.o paracomm.o stdlib.o
 
 wozmon.o: polmon.cc
 wozmon.o: CPPFLAGS = -DWOZMON=1

ftp.asm

@@ -1,6 +1,7 @@
 CPU 8086
 
 chunksize equ 0x20
+devicedelay equ 0x08
 
 _start:
     push bp
@@ -13,24 +14,35 @@ _start:
     mov bx, [bp-8]
     mov [bx], byte 0x42
 l0:
-    cmp word [bp-4], 0xf400
+    cmp word [bp-4], 0xf600
     jb l1
-    add sp, 8
+l2:
+    mov sp, bp
     pop bp
     ret
 l1:
+    mov ah, 0x07
+    int 0x80
+    test al, al
+    jnz l1
     push word [bp-2]
     push word [bp-4]
     mov ah, 0x05
     int 0x80
-    add sp, 4
+    test al, al
+    jz l2
+    mov ah, 0
+    add [bp-4], ax
     push word [bp-6]
     push word [bp-8]
     mov ah, 0x06
     int 0x80
-    add sp, 4
-    add word [bp-4], chunksize
-    mov cx, 0x200
-l2: dec cx
-    jnz l2
+    add sp, 8
+    mov cx, devicedelay
+l3: 
+    mov ah, 0x07
+    push cx
+    int 0x80
+    pop cx
+    loop l3             ; give the device some time to answer
     jmp l0

mushroom.s

@@ -16,13 +16,14 @@ _start:
 
     .section .bss
 kBufSize = 77
-kParaDelay = 500
 kDividerRow = 23
+kRecvBufSize = 128
 
 curpos: .word 0
 inputsize: .byte 0
 escaped: .byte 0
 inputbuf: .zero kBufSize
+recvbuf: .zero kRecvBufSize
 
     # XXX: funky call
     # inputs:
@@ -109,15 +110,6 @@ addtext:
     pop di
     ret
 
-    .section .text.paracb
-paracb:
-    push si
-    mov si, ax
-    mov cl, dl
-    call addtext
-    pop si
-    ret
-
     .section .text.sendbuffer
 sendbuffer:
     push bp
@@ -167,22 +159,17 @@ drawchar:
 
     .section .text.parasend
 parasend:
-1:
-    test cl, cl
-    jz 0f
-    mov al, [si]
+    mov ah, 0x06        # send parallel
     push cx
-    call paracomm_send
-    pop cx
-    test al, al
-    jnz 2f
-    inc si
-    dec cl
-    jmp 1b
-0:
-    mov al, '\n'
-    call paracomm_send
-2:
+    push si
+    int 0x80
+    mov cx, 1
+    push cx
+    mov cx, offset .l1 + 1
+    push cx
+    mov ah, 0x06        # send parallel
+    int 0x80
+    add sp, 8
     ret
     
 prompt:
@@ -212,8 +199,6 @@ main:
     movb escaped, 0
     mov ax, 0x0002
     int 0x10
-    mov ax, offset paracb
-    call paracomm_init
     mov si, offset .l2
     mov cl, l2len
     call addtext
@@ -259,21 +244,18 @@ main:
 4:
     call sendbuffer         # send input buffer
 1:
-    call paracomm_nextbyte
-    mov dx, 0x3bc
-    out dx, al
-    add dl, 2
-    mov al, 1
-    out dx, al
-    mov cx, kParaDelay
-2:  loop 2b    
-    mov al, 0
-    out dx, al
-    mov cx, kParaDelay
-3:  loop 3b    
-    dec dl
-    in al, dx
-    mov cl, 4
-    shr al, cl
-    call paracomm_feed
+    mov ah, 0x07            # do parallel comms
+    int 0x80
+    mov ax, kRecvBufSize
+    push ax
+    mov ax, offset recvbuf
+    push ax
+    mov ah, 0x05            # recv
+    int 0x80
+    test al, al
+    mov cl, al
+    pop si
+    pop bx
+    jz 0b
+    call addtext
     jmp 0b

paracomm.c

@@ -1,6 +1,7 @@
 #include "paracomm.h"
 
 #include <stdlib.h>
+#include <string.h>
 
 #define kMosiIdleByte 0x00
 #define kMosiStartByte 0x42
@@ -21,7 +22,6 @@ static uint8_t miso_recvbuf[256];
 static uint8_t miso_size;
 static uint8_t miso_received_nibbles;
 static uint8_t miso_state;
-static void (*miso_cb)(const uint8_t*, uint8_t);
 
 static void swapbuffers() {
     mosi_sendbuf = mosi_workbuf[mosi_workbuf_idx];
@@ -92,23 +92,19 @@ void paracomm_feed(uint8_t n) {
         miso_received_nibbles += 1;
 
         if (miso_received_nibbles == 2 * miso_size) {
-            if (miso_cb != 0) {
-                miso_cb(miso_recvbuf, miso_size);
-            }
             miso_state = 0;
         }
     } break;
     }
 }
 
-void paracomm_init(miso_cb_t cb) {
+void paracomm_init() {
     mosi_size = 0;
     mosi_workbuf_idx = 0;
     mosi_workbuf_size = 0;
     mosi_state = 0;
 
     miso_state = 0;
-    miso_cb = cb;
 }
 
 int paracomm_send(uint8_t b) {
@@ -122,3 +118,21 @@ int paracomm_send(uint8_t b) {
 
     return 0;
 }
+
+uint8_t paracomm_recv(uint8_t* buf, uint8_t size) {
+    if (miso_state != 0) {
+        return 0;
+    }
+    if (size > miso_size) {
+        size = miso_size;
+    }
+    memcpy(buf, miso_recvbuf, size);
+    memcpy(miso_recvbuf, miso_recvbuf+size, miso_size - size);
+    miso_size -= size;
+
+    return size;
+}
+
+uint8_t paracomm_busy() {
+    return mosi_state != 0 || miso_state != 0;
+}

paracomm.h

@@ -2,18 +2,24 @@
 
 #include <stdint.h>
 
-typedef void (*miso_cb_t)(const uint8_t* buff, uint8_t size);
-
 /** Must call first **/
-void paracomm_init(miso_cb_t miso_cb);
+void paracomm_init();
 
 /** Sends a single byte.
  * Returns: 0 if no error, non-0 otherwise.
  */
 int paracomm_send(uint8_t b);
 
+/** Receive some bytes.
+ * Returns: number of bytes copied
+ */
+uint8_t paracomm_recv(uint8_t* buf, uint8_t size);
+
 /** Call after reading a nibble from the port */
 void paracomm_feed(uint8_t n);
 
 /** Yields the next byte to send out the port */
 uint8_t paracomm_nextbyte();
+
+/** Returns non-zero if busy */
+uint8_t paracomm_busy();

polio-main.c

@@ -1,4 +1,6 @@
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "fat12.h"
 #include "paracomm.h"
@@ -11,21 +13,18 @@
 #define kParallelStatusPort 0x3bd
 #define kParallelControlPort 0x3be
 #define kParaDelay 400
+#define kRecvBufferSize 256
 
 void dosdbt();
 void int80h();
 
-uint8_t* parabuf;
+uint8_t parabuf[kRecvBufferSize];
 uint8_t parasize;
 
 static void paracb(const uint8_t* buf, uint8_t size) {
-    if (size > parasize) {
-        return paracb(buf, parasize);
-    }
-    for (int i = 0; i < size; i++) {
-        parabuf[i] = buf[i];
-    }
-    parasize = 0;
+    // we'll mercilessly erase old data with new data
+    memcpy(parabuf, buf, size);
+    parasize = size;
 }
 
 static void die() {
@@ -52,7 +51,7 @@ static void __delay__(int n) {
     }
 }
 
-static void paraxfer() {
+uint8_t xferpara() {
     uint8_t mosib = paracomm_nextbyte();
     __outb__(kParallelDataPort, mosib);
     __outb__(kParallelControlPort, 1);
@@ -61,30 +60,23 @@ static void paraxfer() {
     __delay__(kParaDelay);
     uint8_t mison = __inb__(kParallelStatusPort) >> 4;
     paracomm_feed(mison);
+
+    return paracomm_busy();
 }
 
-void pararecv(uint8_t* addr, uint8_t size) {
-    parabuf = addr;
-    parasize = size;
-    for (int i = 0; i < 1 + 2 + size * 2; i++) {
-        if (!parasize) {
+uint8_t parasend(uint8_t* addr, uint8_t size) {
+    uint8_t i;
+    for (i = 0; i < size; i++) {
+        if (paracomm_send(addr[i])) {
             break;
         }
-        paraxfer();
-    }
-}
-
-void parasend(uint8_t* addr, uint8_t size) {
-    for (int i = 0; i < size; i++) {
-        paracomm_send(addr[i]);
-    }
-    for (int i = 0; i < size + 2; i++) {
-        paraxfer();
     }
+    return i;
 }
 
 int main() {
     dosdbt();
+    parasize = 0;
     paracomm_init(paracb);
 
     fat12_init(kFatAddr, kRootDirAddr);

polio.s

@@ -143,7 +143,7 @@ recvpara:
     mov ax, [bp+0]
     add ax, si
     mov dx, [bp+2]
-    call pararecv
+    call paracomm_recv
     ret
 
     .section .text.int80h
@@ -186,5 +186,6 @@ int80h_table:
     .word offset readfile       # 0x04
     .word offset recvpara       # 0x05
     .word offset sendpara       # 0x06
+    .word offset xferpara       # 0x07
 
 int80h_entries = . - int80h_table

stdlib.c

@@ -1,3 +1,6 @@
+#include <stdint.h>
+#include <stdlib.h>
+
 int getchar() {
     register char c asm("al");
     asm volatile("movb $0x00, %%ah\n\t"
@@ -23,3 +26,20 @@ int puts(const char* s) {
     }
     return 0;
 }
+
+void* memcpy(void* dest, const void* src, size_t n) {
+    uint8_t* d = dest;
+    const uint8_t* s = src;
+    for (int i = 0; i < n; i++) {
+        d[i] = s[i];
+    }
+    return dest;
+}
+
+void* memset(void* ptr, int val, size_t len) {
+    uint8_t* p = ptr;
+    while (len--) {
+        *p++ = val;
+    }
+    return ptr;
+}