First VCS sample.

Fixed branch target offset.
Fixed empty location removal.

6502.lua

@@ -34,6 +34,7 @@ M.link = function()
         -- filter sections list
         local position_independent_sections = {}
         local symbols_to_remove = {}
+        local section_count = #sections
         location.cycles=0 location.used=0
         for ix,section in ipairs(sections) do
             section:compute_size()
@@ -44,6 +45,9 @@ M.link = function()
                 if not section.org then table.insert(symbols_to_remove, section.label) end
             elseif not section.org then table.insert(position_independent_sections, section) end
         end
+        do local j=0 for i=1,section_count do
+            if sections[i] ~= nil then j=j+1 sections[j],sections[i] = sections[i],sections[j] end
+        end end
         for _,v in ipairs(symbols_to_remove) do symbols[v] = nil end
         stats.cycles = stats.cycles + location.cycles
         stats.used = stats.used + location.used
@@ -255,7 +259,9 @@ stats.__tostring = function()
                 location.unused, location.used, location.stops_at-location.start+1, location.start, location.stops_at))
         end
     end
-    ins(s, string.format(" --- Total ---  %5d %5d %5d", stats.unused, stats.used, stats.bin_size))
+    if #locations > 1 then
+        ins(s, string.format(" --- Total ---  %5d %5d %5d", stats.unused, stats.used, stats.bin_size))
+    end
     return table.concat(s, '\n')
 end
 
@@ -326,10 +332,12 @@ M.section = function(t)
     return section
 end
 
+M.label_gen_ix = 0
 M.label = function(name)
     local label,offset
     local section,rorg = M.section_current,M.location_current.rorg
     label = { type='label' }
+    if not name then name='_L'..M.label_gen_ix M.label_gen_ix=M.label_gen_ix+1 end
     if name:sub(1,1) == '_' then -- local label
         name = M.label_current .. name
     else
@@ -345,7 +353,7 @@ M.label = function(name)
     end
     label.resolve = function() return rorg(section.org + offset) end
     table.insert(section.instructions, label)
-    return label
+    return name,label
 end
 
 M.samepage = function()
@@ -395,10 +403,11 @@ M.charset = function(s, f)
 end
 
 M.byte_impl = function(args, nrm)
+    if #args == 0 then error("byte*() need at least 1 argument") end
     local data,cs = {},M.cs
     for k,v in ipairs(args) do
         local t = type(v)
-        if t == 'number' or t == 'function' then data[#data+1] = v
+        if t == 'number' or t == 'function' or t == 'string' then data[#data+1] = v
         elseif t == 'table' then table.move(v,1,#v,#data+1,data)
         elseif t == 'string' then
             if cs then
@@ -462,10 +471,11 @@ end
 --    after symbols have been resolved
 M.word = function(...)
     local args = {...}
+    if #args == 0 then error("word needs() at least 1 argument") end
     local data = {}
     for k,v in ipairs(args) do
         local t = type(v)
-        if t == 'number' or t == 'function' then data[#data+1] = v
+        if t == 'number' or t == 'function' or t == 'string' then data[#data+1] = v
         elseif t == 'table' then
             if v.type == 'section' or v.type == 'label' then data[#data+1] = function() return symbols[v.label] end
             else table.move(v,1,#v,#data+1,data) end
@@ -729,7 +739,7 @@ for k,v in pairs(oprel) do
                 x = symbols[x]
             end
             if type(x) ~= 'number' then error("unresolved branch target: " .. tostring(x)) end
-            x = x - offset - rorg(section.org)
+            x = x-2 - offset - rorg(section.org)
             if x < -128 or x > 127 then error("branch target out of range for " .. l .. ": " .. x) end
             b[#b+1]=v.opc b[#b+1]=x&0xff
         end

asm.l65

@@ -71,6 +71,7 @@ ptr_table("ptrs", message, data, 0)
     ldx #0b1101
     ldy #0xAB - 16 + 0b11011 & 3 | 6 ~ 0xf >> ~3 << 1 // 5
     ldx #15,3
+    ldx#0
 
     local kernel_cycles,kernel_size
     table.insert(section_current.instructions, { asbin=function() kernel_cycles=cycles kernel_size=size end })

asm.lua

@@ -71,6 +71,7 @@ section("waitForIntim") --alt short syntax when no other option
     ldximm (function(_o) return _o+(13) end)
     ldyimm (function(_o) return _o+(0xAB - 16 + 27 & 3 | 6 ~ 0xf >> ~3 << 1 // 5) end)
     ldximm (function(_o) return _o+(15) end,3)
+    ldximm(function(_o) return _o+(0) end)
 
     local kernel_cycles,kernel_size
     table.insert(section_current.instructions, { asbin=function() kernel_cycles=cycles kernel_size=size end })

samples/vcs1.l65

@@ -0,0 +1,33 @@
+dofile "vcs.lua"
+
+TIM_OVERSCAN    = 50 -- TIM64T,  3200 cycles = ~ 42 scanlines
+TIM_VBLANK      = 61 -- TIM64T,  3904 cycles = ~ 51 scanlines
+TIM_KERNEL      = 17 -- T1024T, 17408 cycles = ~229 scanlines
+
+location(0xf000, 0xffff)
+
+local kernel = function()
+    ldx#0xd0 @_loop sta WSYNC stx COLUBK dex bne _loop
+end
+
+local wait = function() local l=label() lda INTIM bne l end
+
+@@start
+    -- clear zeropage
+    cld ldx#0 txa @_clear dex tsx pha bne _clear
+@main
+    -- overscan
+    sta WSYNC lda#2 sta VBLANK lda#TIM_OVERSCAN sta TIM64T wait()
+    -- vblank
+    lda#0b1110 @_vsync sta WSYNC sta VSYNC lsr bne _vsync
+    lda#2 sta VBLANK lda#TIM_VBLANK sta TIM64T wait() sta WSYNC sta VBLANK
+    -- kernel
+    lda#TIM_KERNEL sta T1024T kernel() wait()
+    jmp main
+
+section{'vectors', org=0xfffc} word(start,start)
+
+local filename=string.match(arg[0], ".-([^\\/]-)%.?[^%.\\/]*$")
+writebin(filename..'.bin')
+writesym(filename..'.sym')
+print(stats)