130 lines
4.4 KiB
Python
Executable File
130 lines
4.4 KiB
Python
Executable File
#!/usr/bin/env python3
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import re
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import fileinput
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# Pass an Xtensa core-isa.h file on stdin or the command line, emits a
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# C file on output containing optimized interrupt dispatch routines.
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# FIXME: looking at the assembly generated by the ESP-32 toolchain,
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# this isn't as optimal as I'd hoped. the individual cases are tested
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# using a L32R + BNONE (i.e. a full mask test) instead of a BBSI, and
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# the handlers are being invoked with CALL8 instead of CALL4,
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# inexplicably wasting four words of stack. Maybe this should be
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# emitting assembly instead. Wouldn't be much more complicated and
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# would share all the same structure.
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# My manual count of instructions says that a linear search becomes
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# faster on average when there are three or fewer bits to test. Would
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# be four, if the compiler would generate BBSI instructions.
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MAX_TESTS = 3
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ints_by_lvl = {}
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# print() wrapper that automatically handles indentation levels
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cindent = 0
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def cprint(s):
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global cindent
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if s.find("}") >= 0:
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cindent -= 1
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for xx in range(cindent):
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s = "\t" + s
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print(s)
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if s.find("{") >= 0:
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cindent += 1
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def emit_int_handler(ints):
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if len(ints) <= MAX_TESTS:
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for i in ints:
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# FIXME: a little work could allow us to extract the
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# handler pointer and argument as literals, saving a few
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# instructions and avoiding the need to link in
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# _sw_isr_table entirely.
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cprint("if (mask & (1 << " + str(i) + ")) {")
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cprint("struct _isr_table_entry *e = &_sw_isr_table[" + str(i) + "];")
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print("");
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cprint("e->isr(e->arg);")
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cprint("return 1 << " + str(i) + ";")
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cprint("}")
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else:
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half = int(len(ints)/2)
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m = 0
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for i in ints[0:half]:
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m |= 1 << i
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cprint("if (mask & " + ("0x%x" % (m)) + ") {")
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emit_int_handler(ints[0:half])
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cprint("} else {")
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emit_int_handler(ints[half:])
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cprint("}")
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########################################################################
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# Annoyingly need to join lines and remove #-marked annotations. Some
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# versions of the preprocessor (ahem, esp32 SDK) like to include
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# newlines in the output where the original expressions are expanded
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# from 100% single line macros. Slurp it into a single string and
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# parse via whitespace.
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blob = ""
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for l in fileinput.input():
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l = l if l.find("#") < 0 else l[0:l.find("#")]
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blob += l.rstrip() + " "
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for match in re.finditer(r'__xtensa_int_level_magic__\s+(\d+)\s+(\d+)', blob):
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irq = int(match.group(1))
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lvl = int(match.group(2))
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if not lvl in ints_by_lvl:
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ints_by_lvl[lvl] = []
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ints_by_lvl[lvl].append(irq)
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cprint("/*")
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cprint(" * THIS FILE WAS AUTOMATICALLY GENERATED. DO NOT EDIT.")
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cprint(" *")
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cprint(" * Functions here are designed to produce efficient code to")
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cprint(" * search an Xtensa bitmask of interrupts, inspecting only those bits")
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cprint(" * declared to be associated with a given interrupt level. Each")
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cprint(" * dispatcher will handle exactly one flagged interrupt, in numerical")
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cprint(" * order (low bits first) and will return a mask of that bit that can")
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cprint(" * then be cleared by the calling code. Unrecognized bits for the")
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cprint(" * level will invoke an error handler.")
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cprint(" */")
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cprint("")
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# Re-include the core-isa header and be sure our definitions match, for sanity
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cprint("#include <xtensa/config/core-isa.h>")
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cprint("#include <sw_isr_table.h>")
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cprint("")
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for l in ints_by_lvl:
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for i in ints_by_lvl[l]:
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v = "XCHAL_INT" + str(i) + "_LEVEL"
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cprint("#if !defined(" + v + ") || " + str(v) + " != " + str(l))
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cprint("#error core-isa.h interrupt level does not match dispatcher!")
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cprint("#endif")
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cprint("")
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# Populate empty levels just for sanity. The second-to-last interrupt
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# level (usually "debug") typically doesn't have any associated
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# vectors, but we don't have any way to know that a-prioi.
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max = 0
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for lvl in ints_by_lvl:
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if lvl > max:
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max = lvl
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for lvl in range(0, max+1):
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if not lvl in ints_by_lvl:
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ints_by_lvl[lvl] = []
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# Emit the handlers
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for lvl in ints_by_lvl:
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cprint("static inline int _xtensa_handle_one_int" + str(lvl) + "(unsigned int mask)")
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cprint("{")
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ints_by_lvl[lvl].sort()
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emit_int_handler(ints_by_lvl[lvl])
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cprint("return 0;")
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cprint("}")
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cprint("")
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