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/* WebAssembly port of the microcore. the page hands the program over as
bytes, calls run(), and gets output back one byte at a time through the
one import. build with src/web/build.sh; nothing here needs libc. */
#include "micro_port.h"
extern void js_putc(int c);
extern void js_msg(int c);
static unsigned char inbuf[1 << 20];
static int inn, inp;
/* where the page writes the program, and how it says how long it is */
unsigned char *wasm_input(void) { return inbuf; }
int wasm_input_cap(void) { return (int)sizeof inbuf; }
void wasm_set_input(int n) { inn = n; inp = 0; }
/* the machine's memory: the linear memory above everything the module has in it.
the base is fixed when the first machine is made, and a grow only adds pages on
the top, so the base never moves. */
static unsigned char *mbase;
static UCell mcap; /* bytes of machine memory the module has grown for */
Cell *micro_mem_alloc(UCell words)
{
UCell need, extra, pages;
if (words > ((UCell)-1) / sizeof(Cell)) return 0;
if (!mbase) {
mbase = (unsigned char *)((UCell)__builtin_wasm_memory_size(0) * 65536u);
mcap = 0;
}
need = words * sizeof(Cell);
if (need <= mcap) return (Cell *)mbase;
extra = need - mcap;
pages = (extra + 65535u) / 65536u;
if (__builtin_wasm_memory_grow(0, (int)pages) < 0) return 0;
mcap += pages * 65536u; /* wasm zeroes the pages it grows by */
return (Cell *)mbase;
}
int micro_getc(void) { return inp < inn ? inbuf[inp++] : -1; }
int micro_eof(void) { return inp >= inn; }
void micro_putc(int c) { js_putc(c & 255); }
void micro_msg(const char *s) { while (*s) js_msg(*s++); }
Cell micro_syscall(Cell *mem, Cell op, Cell a, Cell b, Cell c)
{
switch (op) {
case 9: /* memory: the size of the machine and its heap */
if (a == 0) return micro_mem_words();
if (a == 1) return HEAP_LO;
if (a == 2) return HEAP_HI;
if (a == 3) return (Cell)micro_mem_words() * 8;
return -1;
case 7: /* exit: the page sees run() return */
return -1;
case 21: /* argc: the page has no command line, so <eval> alone */
return 1;
case 22: /* argv: entry 0 is <eval>, as in zy(1) */
if (a != 0) return -1;
if (!b) return 6;
if (c < 7 || b + 6 >= micro_mem_words()) return -1;
{
static const char lead[] = "<eval>";
int i;
for (i = 0; i < 6; i++) mem[b + i] = (unsigned char)lead[i];
mem[b + 6] = 0;
}
return 6;
case 23: /* envc: a page has no environment */
return 0;
}
return -1;
}
/* the core multiplies 64 by 64 into 128 bits for the float helpers; wasm has no
such instruction and there is no compiler runtime to link, so this is it */
void __multi3(unsigned long long *r, unsigned long long al, unsigned long long ah, unsigned long long bl, unsigned long long bh)
{
unsigned long long a0 = al & 0xffffffffu, a1 = al >> 32, b0 = bl & 0xffffffffu, b1 = bl >> 32;
unsigned long long p00 = a0 * b0, p01 = a0 * b1, p10 = a1 * b0, p11 = a1 * b1;
unsigned long long mid = (p00 >> 32) + (p01 & 0xffffffffu) + (p10 & 0xffffffffu);
r[0] = (p00 & 0xffffffffu) | (mid << 32);
r[1] = p11 + (p01 >> 32) + (p10 >> 32) + (mid >> 32) + al * bh + ah * bl;
}
int wasm_run(void) { return micro_run(); }
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