z80: update banking documentation

diff --git a/Kernel/doc/SDCCBanking b/Kernel/doc/SDCCBanking
index 0e83f9a..26b02c9 100644 (file)
--- a/Kernel/doc/SDCCBanking
+++ b/Kernel/doc/SDCCBanking
@@ -24,7 +24,7 @@ Code Segments:
        _CODE2          is "bank 2"
        _CODE3          is "bank 3"
        _VIDEO          is "bank 3"
-       _DISCARD        is "bank 3"
+       _DISCARD        is common (bank 0)
        _COMMONMEM      is common (bank 0)
 
 Data Segments:
@@ -76,33 +76,36 @@ break. Hopefully SDCC never decides to create one behind our back.
 
 Stubs:
 
-       CALL __bank_n_from_m
-       defw xx
-       RET
+either
+
+       LD DE, #function
+       JP __stub_n_from_m
+
+or
+
+       LD HL, #function
+       JP __stub_n_from_0
+
 
 The stubs may live in the bank of the invoking function, while __bank_x is
-common
+common.
 
 This is done to process tables. It means that function tables like device or
 syscall tables correctly generate inter bank calls.
 
 Banking Handlers
 
+See platform-zx128/zx128.s
+
+
+Assumptions
+
+__sdcc_callhl
+__enter
+__enter_s
+
+must live in common memory
+
+You must use a sdcc support library modified to expect 'far' style offsets
+on helpers, but they may be banked.
 
-__bank_0_from_1:
-       POP HL                  ; return
-       LD DE, (HL)
-       INC HL
-       LD D, (HL)
-       INC HL
-       PUSH HL                 ; true return
-       LD A, #bank0op
-       OUT (port), A
-       EX DE, HL
-       CALL __callhl
-__bank1_ret:
-       LD A, #1
-       OUT (port), A
-       RET
-__callhl:
-       JP (HL)
\ No newline at end of file