Differences

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--- wswan:guide:memory_management [2025/04/03 18:10] – asie
+++ wswan:guide:memory_management [2025/08/15 10:33] (current) – [Advanced section names] asie
@@ Line 13: / Line 13: @@
 <code C>
-// The variable below will be stored in IRAM, even if it's declared const.
+// The variable below will be stored in IRAM, even if it's declared as read-only (const).
 static const uint16_t table_iram[] = {0, 1, 2, 3};
-// The variable below will now be stored in ROM instead of IRAM.
+// The variable below will now be stored in ROM instead of IRAM, as it is read-only and far.
 static const uint16_t __far table[] = {0, 1, 2, 3};
+// As will this one, except it's not static, so you can reference it in a .h file...
+const uint16_t __far global_table[] = {0, 1, 2, 3};
+// ... like so.
+extern const uint16_t __far global_table[];
 void process_table_iram(uint16_t *tbl); // This function can accept pointers to IRAM only.
@@ Line 38: / Line 44: @@
   * ''.fartext'' - far code, last 768 KiB of ROM
-  * ''.farrodata'' - far data, last 768 KiB of ROM
+  * ''.farrodata'' - far read-only data, last 768 KiB of ROM
   * ''.text'' - code, RAM
   * ''.rodata'', ''.data'' - data, RAM
@@ Line 48: / Line 54: @@
 <code>
-    .section .fartext.my_asm_code, "ax"
+.section .fartext.my_rom_code_segment, "ax"
-    .section .farrodata.my_asm_data, "a"
+.section .farrodata.my_rom_data_segment, "a"
+.section .text.my_ram_code, "ax"
+.section .data.my_ram_data, "aw"
 </code>
-The quoted component refers to section flags. The most useful ones are:
+The quoted component at the end, like ''"ax"'', contains the ELF flags for a given section. These are not optional! The most useful ones are:
-  * ''a'' - section is allocated in RAM/ROM
+  * ''a'' - section is allocated in RAM/ROM; if not used, the binary may end up not containing the data at all!
   * ''w'' - section is writable
   * ''x'' - section is executable
-  * ''R'' - section is retained even if not used by any code
+  * ''R'' - section is retained, even if not used by any code
 All section flags are listed in [[https://wonderful.asie.pl/doc/binutils-ia16/as.html#Section-Name-Substitutions|the assembler manual]].
@@ Line 97: / Line 105: @@
 with the following optional arguments:
-  * **bank index** - the index of a bank, padded to the top of ROM.
+  * **bank index** - the index of a bank, in hexadecimal, padded to the top of ROM. For example, ''.rom0_f'' always refers to the final bank, even if the ROM has more than 16 banks.
-  * **offset** - the absolute offset within a bank or memory location.
+  * **offset** - the absolute offset within a bank or memory location, in hexademical. For example, ''.rom0_ffff_1234'' would place at location ''0x..FFFF1234'' in the cartridge image.
 Note that the linker requires //distinct// section names to place things separately: in other banks, memory locations, or for garbage collection. One can use ''.'' after the prefix to specify an unique name.