Optimize diskio.f_read for size=1, also improve ST check

compiler/res/prog8lib/cx16/diskio.p8

@@ -327,8 +327,19 @@ close_end:
             return 0
 
         reset_read_channel()
-        list_blocks = 0     ; we reuse this variable for the total number of bytes read
+        if num_bytes==1 {
+            ; optimize for reading just a single byte
+            @(bufferpointer) = cbm.CHRIN()
+            cx16.r0L = cbm.READST()
+            if cx16.r0L!=0 {
+                f_close()
+                if cx16.r0L & $40 == 0
+                    return 0
+            }
+            return 1
+        }
 
+        list_blocks = 0     ; we reuse this variable for the total number of bytes read
         uword readsize
         while num_bytes!=0 {
             readsize = 255
@@ -357,12 +368,6 @@ byte_read_loop:         ; fallback if MACPTR isn't supported on the device
             sta  m_in_buffer+2
         }}
         while num_bytes!=0 {
-            if cbm.READST()!=0 {
-                f_close()
-                if cbm.READST() & $40 !=0    ; eof?
-                    return list_blocks   ; number of bytes read
-                return 0  ; error.
-            }
             %asm {{
                 jsr  cbm.CHRIN
 m_in_buffer     sta  $ffff
@@ -371,6 +376,13 @@ m_in_buffer     sta  $ffff
                 inc  m_in_buffer+2
 +
             }}
+            cx16.r0L = cbm.READST()
+            if cx16.r0L!=0 {
+                f_close()
+                if cx16.r0L & $40 !=0    ; eof?
+                    return list_blocks   ; number of bytes read
+                return 0  ; error.
+            }
             list_blocks++
             num_bytes--
         }

compiler/res/prog8lib/shared_cbm_diskio.p8

@@ -303,8 +303,19 @@ close_end:
             return 0
 
         reset_read_channel()
-        list_blocks = 0     ; we reuse this variable for the total number of bytes read
+        if num_bytes==1 {
+            ; slightly optimized path for reading just a single byte
+            @(bufferpointer) = cbm.CHRIN()
+            cx16.r0L = cbm.READST()
+            if cx16.r0L!=0 {
+                f_close()
+                if cx16.r0L & $40 == 0
+                    return 0
+            }
+            return 1
+        }
 
+        list_blocks = 0     ; we reuse this variable for the total number of bytes read
         %asm {{
             lda  bufferpointer
             sta  m_in_buffer+1
@@ -312,12 +323,6 @@ close_end:
             sta  m_in_buffer+2
         }}
         while num_bytes!=0 {
-            if cbm.READST()!=0 {
-                f_close()
-                if cbm.READST() & $40 !=0    ; eof?
-                    return list_blocks   ; number of bytes read
-                return 0  ; error.
-            }
             %asm {{
                 jsr  cbm.CHRIN
 m_in_buffer     sta  $ffff
@@ -326,6 +331,13 @@ m_in_buffer     sta  $ffff
                 inc  m_in_buffer+2
 +
             }}
+            cx16.r0L = cbm.READST()
+            if cx16.r0L!=0 {
+                f_close()
+                if cx16.r0L & $40 !=0    ; eof?
+                    return list_blocks   ; number of bytes read
+                return 0  ; error.
+            }
             list_blocks++
             num_bytes--
         }

docs/source/todo.rst

@@ -3,9 +3,11 @@ TODO
 
 Fix diskio (cx16, possibly other cbm targets too?) when opening write file , read file stops working
 
+add a -plain option to turn off text output coloring and unicode symbols in error messages (footguns)
 make a compiler switch to disable footgun warnings  -ignorefootguns
 
-update zsmkit to newest version that includes the on_deck routines
+update zsmkit to newest version that includes the on_deck routines when stabilized
+
 
 ...
 

examples/test.p8

@@ -1,14 +1,40 @@
 %import textio
+%import diskio
 %option no_sysinit
 %zeropage basicsafe
 
 main {
     sub start() {
-        ubyte @shared index
+        txt.print("----with read 1:\n")
-        bool @shared success = index==0 or index==255
+        testread1()
-        if success
+        txt.print("----with readline:\n")
-            txt.print("yo")
+        testreadline()
-        if index==0 or index==255
+    }
-            txt.print("yo")
+
+    sub testread1() {
+        if not diskio.f_open("lines.txt")
+            return
+        defer diskio.f_close()
+
+        str buffer = " "
+        while 1==diskio.f_read(&buffer, 1) {
+            txt.chrout(buffer[0])
+        }
+    }
+
+    sub testreadline() {
+        if not diskio.f_open("lines.txt")
+            return
+        defer diskio.f_close()
+
+        str buffer = " "*80
+        ubyte length, status
+        do {
+            length, status = diskio.f_readline(&buffer)
+            if length!=0 {
+                txt.print(buffer)
+                txt.nl()
+            }
+        } until status!=0
     }
 }