mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-10 03:54:48 +00:00
1037 lines
16 KiB
ArmAsm
1037 lines
16 KiB
ArmAsm
; SF format is:
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;
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; [sign] 1.[23bits] E[8bits(n-127)]
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;
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; SEEEEEEE Emmmmmmm mmmmmmmm mmmmmmmm
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;
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; [A+0] mmmmmmmm
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; [A+1] mmmmmmmm
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; [A+2] Emmmmmmm
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; [A+3] SEEEEEEE
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;
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; Special values (xxx != 0):
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;
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; r11 r10 r9 r8
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; [HL+3] [HL+2] [HL+1] [HL+0]
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; s1111111 10000000 00000000 00000000 infinity
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; s1111111 1xxxxxxx xxxxxxxx xxxxxxxx NaN
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; s0000000 00000000 00000000 00000000 zero
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; s0000000 0xxxxxxx xxxxxxxx xxxxxxxx denormals
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;
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; Note that CMPtype is "signed char" for rl78
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;
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#include "vregs.h"
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#define Z PSW.6
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; External Functions:
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;
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; __int_isnan [HL] -> Z if NaN
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; __int_iszero [HL] -> Z if zero
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START_FUNC __int_isinf
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;; [HL] points to value, returns Z if it's #Inf
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mov a, [hl+2]
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and a, #0x80
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mov x, a
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mov a, [hl+3]
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and a, #0x7f
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cmpw ax, #0x7f80
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skz
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ret ; return NZ if not NaN
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mov a, [hl+2]
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and a, #0x7f
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or a, [hl+1]
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or a, [hl]
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ret
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END_FUNC __int_isinf
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#define A_SIGN [hl+0] /* byte */
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#define A_EXP [hl+2] /* word */
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#define A_FRAC_L [hl+4] /* word */
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#define A_FRAC_LH [hl+5] /* byte */
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#define A_FRAC_H [hl+6] /* word or byte */
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#define A_FRAC_HH [hl+7] /* byte */
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#define B_SIGN [hl+8]
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#define B_EXP [hl+10]
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#define B_FRAC_L [hl+12]
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#define B_FRAC_LH [hl+13]
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#define B_FRAC_H [hl+14]
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#define B_FRAC_HH [hl+15]
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START_FUNC _int_unpack_sf
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;; convert 32-bit SFmode [DE] to 6-byte struct [HL] ("A")
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mov a, [de+3]
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sar a, 7
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mov A_SIGN, a
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movw ax, [de+2]
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and a, #0x7f
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shrw ax, 7
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movw bc, ax ; remember if the exponent is all zeros
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subw ax, #127 ; exponent is now non-biased
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movw A_EXP, ax
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movw ax, [de]
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movw A_FRAC_L, ax
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mov a, [de+2]
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and a, #0x7f
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cmp0 c ; if the exp is all zeros, it's denormal
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skz
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or a, #0x80
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mov A_FRAC_H, a
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mov a, #0
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mov A_FRAC_HH, a
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;; rounding-bit-shift
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movw ax, A_FRAC_L
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shlw ax, 1
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movw A_FRAC_L, ax
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mov a, A_FRAC_H
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rolc a, 1
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mov A_FRAC_H, a
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mov a, A_FRAC_HH
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rolc a, 1
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mov A_FRAC_HH, a
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ret
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END_FUNC _int_unpack_sf
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; func(SF a,SF b)
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; [SP+4..7] a
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; [SP+8..11] b
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START_FUNC ___subsf3
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;; a - b => a + (-b)
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;; Note - we cannot just change the sign of B on the stack and
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;; then fall through into __addsf3. The stack'ed value may be
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;; used again (it was created by our caller after all). Instead
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;; we have to allocate some stack space of our own, copy A and B,
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;; change the sign of B, call __addsf3, release the allocated stack
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;; and then return.
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subw sp, #8
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movw ax, [sp+4+8]
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movw [sp], ax
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movw ax, [sp+4+2+8]
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movw [sp+2], ax
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movw ax, [sp+4+4+8]
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movw [sp+4], ax
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mov a, [sp+4+6+8]
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mov [sp+6], a
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mov a, [sp+4+7+8]
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xor a, #0x80
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mov [sp+7], a
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call $!___addsf3
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addw sp, #8
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ret
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END_FUNC ___subsf3
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START_FUNC ___addsf3
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;; if (isnan(a)) return a
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movw ax, sp
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addw ax, #4
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movw hl, ax
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call !!__int_isnan
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bnz $1f
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ret_a:
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movw ax, [sp+4]
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movw r8, ax
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movw ax, [sp+6]
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movw r10, ax
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ret
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1: ;; if (isnan (b)) return b;
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movw ax, sp
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addw ax, #8
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movw hl, ax
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call !!__int_isnan
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bnz $2f
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ret_b:
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movw ax, [sp+8]
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movw r8, ax
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movw ax, [sp+10]
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movw r10, ax
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ret
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2: ;; if (isinf (a))
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movw ax, sp
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addw ax, #4
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movw hl, ax
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call $!__int_isinf
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bnz $3f
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;; if (isinf (b) && a->sign != b->sign) return NaN
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movw ax, sp
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addw ax, #8
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movw hl, ax
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call $!__int_isinf
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bnz $ret_a
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mov a, [sp+7]
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mov h, a
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mov a, [sp+11]
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xor a, h
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bf a.7, $ret_a
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movw r8, #0x0001
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movw r10, #0x7f80
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ret
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3: ;; if (isinf (b)) return b;
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movw ax, sp
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addw ax, #8
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movw hl, ax
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call $!__int_isinf
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bz $ret_b
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;; if (iszero (b))
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movw ax, sp
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addw ax, #8
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movw hl, ax
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call !!__int_iszero
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bnz $4f
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;; if (iszero (a))
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movw ax, sp
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addw ax, #4
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movw hl, ax
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call !!__int_iszero
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bnz $ret_a
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movw ax, [sp+4]
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movw r8, ax
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mov a, [sp+7]
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mov h, a
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movw ax, [sp+10]
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and a, h
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movw r10, ax
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ret
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4: ;; if (iszero (a)) return b;
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movw ax, sp
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addw ax, #4
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movw hl, ax
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call !!__int_iszero
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bz $ret_b
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; Normalize the two numbers relative to each other. At this point,
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; we need the numbers converted to their "unpacked" format.
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subw sp, #16 ; Save room for two unpacked values.
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movw ax, sp
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movw hl, ax
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addw ax, #16+4
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movw de, ax
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call $!_int_unpack_sf
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movw ax, sp
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addw ax, #8
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movw hl, ax
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addw ax, #16+8-8
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movw de, ax
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call $!_int_unpack_sf
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movw ax, sp
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movw hl, ax
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;; diff = a.exponent - b.exponent
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movw ax, B_EXP ; sign/exponent word
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movw bc, ax
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movw ax, A_EXP ; sign/exponent word
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subw ax, bc ; a = a.exp - b.exp
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movw de, ax ; d = sdiff
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;; if (diff < 0) diff = -diff
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bf a.7, $1f
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xor a, #0xff
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xor r_0, #0xff ; x
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incw ax ; a = diff
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1:
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;; if (diff >= 23) zero the smaller one
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cmpw ax, #24
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bc $.L661 ; if a < 23 goto 661
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;; zero out the smaller one
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movw ax, de
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bt a.7, $1f ; if sdiff < 0 (a_exp < b_exp) goto 1f
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;; "zero out" b
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movw ax, A_EXP
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movw B_EXP, ax
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movw ax, #0
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movw B_FRAC_L, ax
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movw B_FRAC_H, ax
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br $5f
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1:
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;; "zero out" a
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movw ax, B_EXP
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movw A_EXP, ax
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movw ax, #0
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movw A_FRAC_L, ax
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movw A_FRAC_H, ax
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br $5f
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.L661:
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;; shift the smaller one so they have the same exponents
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1:
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movw ax, de
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bt a.7, $1f
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cmpw ax, #0 ; sdiff > 0
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bnh $1f ; if (sdiff <= 0) goto 1f
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decw de
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incw B_EXP ; because it's [HL+byte]
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movw ax, B_FRAC_H
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shrw ax, 1
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movw B_FRAC_H, ax
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mov a, B_FRAC_LH
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rorc a, 1
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mov B_FRAC_LH, a
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mov a, B_FRAC_L
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rorc a, 1
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mov B_FRAC_L, a
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br $1b
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1:
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movw ax, de
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bf a.7, $1f
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incw de
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incw A_EXP ; because it's [HL+byte]
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movw ax, A_FRAC_H
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shrw ax, 1
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movw A_FRAC_H, ax
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mov a, A_FRAC_LH
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rorc a, 1
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mov A_FRAC_LH, a
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mov a, A_FRAC_L
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rorc a, 1
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mov A_FRAC_L, a
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br $1b
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1:
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5: ;; At this point, A and B have the same exponent.
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mov a, A_SIGN
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cmp a, B_SIGN
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bnz $1f
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;; Same sign, just add.
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movw ax, A_FRAC_L
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addw ax, B_FRAC_L
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movw A_FRAC_L, ax
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mov a, A_FRAC_H
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addc a, B_FRAC_H
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mov A_FRAC_H, a
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mov a, A_FRAC_HH
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addc a, B_FRAC_HH
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mov A_FRAC_HH, a
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br $.L728
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1: ;; Signs differ - A has A_SIGN still.
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bf a.7, $.L696
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;; A is negative, do B-A
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movw ax, B_FRAC_L
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subw ax, A_FRAC_L
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movw A_FRAC_L, ax
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mov a, B_FRAC_H
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subc a, A_FRAC_H
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mov A_FRAC_H, a
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mov a, B_FRAC_HH
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subc a, A_FRAC_HH
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mov A_FRAC_HH, a
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br $.L698
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.L696:
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;; B is negative, do A-B
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movw ax, A_FRAC_L
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subw ax, B_FRAC_L
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movw A_FRAC_L, ax
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mov a, A_FRAC_H
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subc a, B_FRAC_H
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mov A_FRAC_H, a
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mov a, A_FRAC_HH
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subc a, B_FRAC_HH
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mov A_FRAC_HH, a
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.L698:
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;; A is still A_FRAC_HH
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bt a.7, $.L706
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;; subtraction was positive
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mov a, #0
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mov A_SIGN, a
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br $.L712
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.L706:
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;; subtraction was negative
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mov a, #0xff
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mov A_SIGN, a
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;; This negates A_FRAC
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mov a, A_FRAC_L
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xor a, #0xff ; XOR doesn't mess with carry
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add a, #1 ; INC doesn't set the carry
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mov A_FRAC_L, a
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mov a, A_FRAC_LH
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xor a, #0xff
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addc a, #0
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mov A_FRAC_LH, a
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mov a, A_FRAC_H
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xor a, #0xff
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addc a, #0
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mov A_FRAC_H, a
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mov a, A_FRAC_HH
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xor a, #0xff
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addc a, #0
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mov A_FRAC_HH, a
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.L712:
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;; Renormalize the subtraction
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mov a, A_FRAC_L
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or a, A_FRAC_LH
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or a, A_FRAC_H
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or a, A_FRAC_HH
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bz $.L728
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;; Mantissa is not zero, left shift until the MSB is in the
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;; right place
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1:
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movw ax, A_FRAC_H
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cmpw ax, #0x0200
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bnc $.L728
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decw A_EXP
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movw ax, A_FRAC_L
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shlw ax, 1
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movw A_FRAC_L, ax
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movw ax, A_FRAC_H
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rolwc ax, 1
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movw A_FRAC_H, ax
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br $1b
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.L728:
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;; normalize A and pack it
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movw ax, A_FRAC_H
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cmpw ax, #0x01ff
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bnh $1f
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;; overflow in the mantissa; adjust
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movw ax, A_FRAC_H
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shrw ax, 1
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movw A_FRAC_H, ax
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mov a, A_FRAC_LH
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rorc a, 1
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mov A_FRAC_LH, a
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mov a, A_FRAC_L
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rorc a, 1
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mov A_FRAC_L, a
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incw A_EXP
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1:
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call $!__rl78_int_pack_a_r8
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addw sp, #16
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ret
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END_FUNC ___addsf3
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START_FUNC __rl78_int_pack_a_r8
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;; pack A to R8
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movw ax, A_EXP
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addw ax, #126 ; not 127, we want the "bt/bf" test to check for denormals
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bf a.7, $1f
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;; make a denormal
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2:
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movw bc, ax
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movw ax, A_FRAC_H
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shrw ax, 1
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movw A_FRAC_H, ax
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mov a, A_FRAC_LH
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rorc a, 1
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mov A_FRAC_LH, a
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mov a, A_FRAC_L
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rorc a, 1
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mov A_FRAC_L, a
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movw ax, bc
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incw ax
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bt a.7, $2b
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decw ax
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1:
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incw ax ; now it's as if we added 127
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movw A_EXP, ax
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cmpw ax, #0xfe
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bnh $1f
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;; store #Inf instead
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mov a, A_SIGN
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or a, #0x7f
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mov x, #0x80
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movw r10, ax
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movw r8, #0
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ret
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1:
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bf a.7, $1f ; note AX has EXP at top of loop
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;; underflow, denormal?
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movw ax, A_FRAC_H
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shrw ax, 1
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movw A_FRAC_H, ax
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mov a, A_FRAC_LH
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rorc a, 1
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movw A_FRAC_LH, ax
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mov a, A_FRAC_L
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rorc a, 1
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movw A_FRAC_L, ax
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incw A_EXP
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movw ax, A_EXP
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br $1b
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1:
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;; undo the rounding-bit-shift
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mov a, A_FRAC_L
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bf a.0, $1f
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;; round up
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movw ax, A_FRAC_L
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addw ax, #1
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movw A_FRAC_L, ax
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bnc $1f
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incw A_FRAC_H
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;; If the rounding set the bit beyond the end of the fraction, increment the exponent.
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mov a, A_FRAC_HH
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bf a.1, $1f
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incw A_EXP
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1:
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movw ax, A_FRAC_H
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shrw ax, 1
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movw A_FRAC_H, ax
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mov a, A_FRAC_LH
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rorc a, 1
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mov A_FRAC_LH, a
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mov a, A_FRAC_L
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rorc a, 1
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mov A_FRAC_L, a
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movw ax, A_FRAC_L
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movw r8, ax
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or a, x
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or a, A_FRAC_H
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or a, A_FRAC_HH
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bnz $1f
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movw ax, #0
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movw A_EXP, ax
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1:
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mov a, A_FRAC_H
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and a, #0x7f
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mov b, a
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mov a, A_EXP
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shl a, 7
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or a, b
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mov r10, a
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mov a, A_SIGN
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and a, #0x80
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mov b, a
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mov a, A_EXP
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shr a, 1
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or a, b
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mov r11, a
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ret
|
|
END_FUNC __rl78_int_pack_a_r8
|
|
|
|
START_FUNC ___mulsf3
|
|
|
|
;; if (isnan(a)) return a
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call !!__int_isnan
|
|
bnz $1f
|
|
mret_a:
|
|
movw ax, [sp+4]
|
|
movw r8, ax
|
|
mov a, [sp+11]
|
|
and a, #0x80
|
|
mov b, a
|
|
movw ax, [sp+6]
|
|
xor a, b ; sign is always a ^ b
|
|
movw r10, ax
|
|
ret
|
|
1:
|
|
;; if (isnan (b)) return b;
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_isnan
|
|
bnz $1f
|
|
mret_b:
|
|
movw ax, [sp+8]
|
|
movw r8, ax
|
|
mov a, [sp+7]
|
|
and a, #0x80
|
|
mov b, a
|
|
movw ax, [sp+10]
|
|
xor a, b ; sign is always a ^ b
|
|
movw r10, ax
|
|
ret
|
|
1:
|
|
;; if (isinf (a)) return (b==0) ? nan : a
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call $!__int_isinf
|
|
bnz $.L805
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bnz $mret_a
|
|
|
|
movw r8, #0x0001 ; return NaN
|
|
movw r10, #0x7f80
|
|
ret
|
|
|
|
.L805:
|
|
;; if (isinf (b)) return (a==0) ? nan : b
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call $!__int_isinf
|
|
bnz $.L814
|
|
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bnz $mret_b
|
|
|
|
movw r8, #0x0001 ; return NaN
|
|
movw r10, #0x7f80
|
|
ret
|
|
|
|
.L814:
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bz $mret_a
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bz $mret_b
|
|
|
|
;; at this point, we're doing the multiplication.
|
|
|
|
subw sp, #16 ; save room for two unpacked values
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
addw ax, #16+4
|
|
movw de, ax
|
|
call $!_int_unpack_sf
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
addw ax, #16+8-8
|
|
movw de, ax
|
|
call $!_int_unpack_sf
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
|
|
;; multiply SI a.FRAC * SI b.FRAC to DI r8
|
|
|
|
subw sp, #16
|
|
movw ax, A_FRAC_L
|
|
movw [sp+0], ax
|
|
movw ax, A_FRAC_H
|
|
movw [sp+2], ax
|
|
|
|
movw ax, B_FRAC_L
|
|
movw [sp+8], ax
|
|
movw ax, B_FRAC_H
|
|
movw [sp+10], ax
|
|
|
|
movw ax, #0
|
|
movw [sp+4], ax
|
|
movw [sp+6], ax
|
|
movw [sp+12], ax
|
|
movw [sp+14], ax
|
|
|
|
call !!___muldi3 ; MTMPa * MTMPb -> R8..R15
|
|
addw sp, #16
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
|
|
;; add the exponents together
|
|
movw ax, A_EXP
|
|
addw ax, B_EXP
|
|
movw bc, ax ; exponent in BC
|
|
|
|
;; now, re-normalize the DI value in R8..R15 to have the
|
|
;; MSB in the "right" place, adjusting BC as we shift it.
|
|
|
|
;; The value will normally be in this range:
|
|
;; R15 R8
|
|
;; 0001_0000_0000_0000
|
|
;; 0003_ffff_fc00_0001
|
|
|
|
;; so to speed it up, we normalize to:
|
|
;; 0001_xxxx_xxxx_xxxx
|
|
;; then extract the bytes we want (r11-r14)
|
|
|
|
1:
|
|
mov a, r15
|
|
cmp0 a
|
|
bnz $2f
|
|
mov a, r14
|
|
and a, #0xfe
|
|
bz $1f
|
|
2:
|
|
;; shift right, inc exponent
|
|
movw ax, r14
|
|
shrw ax, 1
|
|
movw r14, ax
|
|
mov a, r13
|
|
rorc a, 1
|
|
mov r13, a
|
|
mov a, r12
|
|
rorc a, 1
|
|
mov r12, a
|
|
mov a, r11
|
|
rorc a, 1
|
|
mov r11, a
|
|
;; we don't care about r8/r9/r10 if we're shifting this way
|
|
incw bc
|
|
br $1b
|
|
1:
|
|
mov a, r15
|
|
or a, r14
|
|
bnz $1f
|
|
;; shift left, dec exponent
|
|
movw ax, r8
|
|
shlw ax, 1
|
|
movw r8, ax
|
|
movw ax, r10
|
|
rolwc ax, 1
|
|
movw r10, ax
|
|
movw ax, r12
|
|
rolwc ax, 1
|
|
movw r12, ax
|
|
movw ax, r14
|
|
rolwc ax, 1
|
|
movw r14, ax
|
|
decw bc
|
|
br $1b
|
|
1:
|
|
;; at this point, FRAC is in R11..R14 and EXP is in BC
|
|
movw ax, bc
|
|
movw A_EXP, ax
|
|
|
|
mov a, r11
|
|
mov A_FRAC_L, a
|
|
mov a, r12
|
|
mov A_FRAC_LH, a
|
|
mov a, r13
|
|
mov A_FRAC_H, a
|
|
mov a, r14
|
|
mov A_FRAC_HH, a
|
|
|
|
mov a, A_SIGN
|
|
xor a, B_SIGN
|
|
mov A_SIGN, a
|
|
|
|
call $!__rl78_int_pack_a_r8
|
|
|
|
addw sp, #16
|
|
ret
|
|
|
|
END_FUNC ___mulsf3
|
|
|
|
START_FUNC ___divsf3
|
|
|
|
;; if (isnan(a)) return a
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call !!__int_isnan
|
|
bnz $1f
|
|
dret_a:
|
|
movw ax, [sp+4]
|
|
movw r8, ax
|
|
mov a, [sp+11]
|
|
and a, #0x80
|
|
mov b, a
|
|
movw ax, [sp+6]
|
|
xor a, b ; sign is always a ^ b
|
|
movw r10, ax
|
|
ret
|
|
1:
|
|
;; if (isnan (b)) return b;
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_isnan
|
|
bnz $1f
|
|
dret_b:
|
|
movw ax, [sp+8]
|
|
movw r8, ax
|
|
mov a, [sp+7]
|
|
and a, #0x80
|
|
mov b, a
|
|
movw ax, [sp+10]
|
|
xor a, b ; sign is always a ^ b
|
|
movw r10, ax
|
|
ret
|
|
1:
|
|
|
|
;; if (isinf (a)) return isinf(b) ? nan : a
|
|
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call $!__int_isinf
|
|
bnz $1f
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call $!__int_isinf
|
|
bnz $dret_a
|
|
dret_nan:
|
|
movw r8, #0x0001 ; return NaN
|
|
movw r10, #0x7f80
|
|
ret
|
|
|
|
1:
|
|
|
|
;; if (iszero (a)) return iszero(b) ? nan : a
|
|
|
|
movw ax, sp
|
|
addw ax, #4
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bnz $1f
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bnz $dret_a
|
|
br $dret_nan
|
|
|
|
1:
|
|
;; if (isinf (b)) return 0
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call $!__int_isinf
|
|
bnz $1f
|
|
|
|
mov a, [sp+7]
|
|
mov b, a
|
|
mov a, [sp+11]
|
|
xor a, b
|
|
and a, #0x80
|
|
mov r11, a
|
|
movw r8, #0
|
|
mov r10, #0
|
|
ret
|
|
|
|
1:
|
|
;; if (iszero (b)) return Inf
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
call !!__int_iszero
|
|
bnz $1f
|
|
|
|
mov a, [sp+7]
|
|
mov b, a
|
|
mov a, [sp+11]
|
|
xor a, b
|
|
or a, #0x7f
|
|
mov r11, a
|
|
movw r8, #0
|
|
mov r10, #0x80
|
|
ret
|
|
1:
|
|
|
|
;; at this point, we're doing the division. Normalized
|
|
;; mantissas look like:
|
|
;; 01.xx.xx.xx
|
|
;; so we divide:
|
|
;; 01.xx.xx.xx.00.00.00.00
|
|
;; by 01.xx.xx.xx
|
|
;; to get approx 00.80.00.00.00 to 01.ff.ff.ff.00
|
|
|
|
|
|
subw sp, #16 ; save room for two unpacked values
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
addw ax, #16+4
|
|
movw de, ax
|
|
call $!_int_unpack_sf
|
|
|
|
movw ax, sp
|
|
addw ax, #8
|
|
movw hl, ax
|
|
addw ax, #16+8-8
|
|
movw de, ax
|
|
call $!_int_unpack_sf
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
|
|
;; divide DI a.FRAC / SI b.FRAC to DI r8
|
|
|
|
subw sp, #16
|
|
movw ax, A_FRAC_L
|
|
movw [sp+4], ax
|
|
movw ax, A_FRAC_H
|
|
movw [sp+6], ax
|
|
|
|
movw ax, B_FRAC_L
|
|
movw [sp+8], ax
|
|
movw ax, B_FRAC_H
|
|
movw [sp+10], ax
|
|
|
|
movw ax, #0
|
|
movw [sp+0], ax
|
|
movw [sp+2], ax
|
|
movw [sp+12], ax
|
|
movw [sp+14], ax
|
|
|
|
call !!___divdi3 ; MTMPa / MTMPb -> R8..R15
|
|
addw sp, #16
|
|
|
|
movw ax, sp
|
|
movw hl, ax
|
|
|
|
;; subtract the exponents A - B
|
|
movw ax, A_EXP
|
|
subw ax, B_EXP
|
|
movw bc, ax ; exponent in BC
|
|
|
|
;; now, re-normalize the DI value in R8..R15 to have the
|
|
;; MSB in the "right" place, adjusting BC as we shift it.
|
|
|
|
;; The value will normally be in this range:
|
|
;; R15 R8
|
|
;; 0000_0000_8000_0000
|
|
;; 0000_0001_ffff_ff00
|
|
|
|
;; so to speed it up, we normalize to:
|
|
;; 0000_0001_xxxx_xxxx
|
|
;; then extract the bytes we want (r9-r12)
|
|
|
|
1:
|
|
movw ax, r14
|
|
cmpw ax, #0
|
|
bnz $2f
|
|
movw ax, r12
|
|
cmpw ax, #1
|
|
bnh $1f
|
|
2:
|
|
;; shift right, inc exponent
|
|
movw ax, r14
|
|
shrw ax, 1
|
|
movw r14, ax
|
|
mov a, r13
|
|
rorc a, 1
|
|
mov r13, a
|
|
mov a, r12
|
|
rorc a, 1
|
|
mov r12, a
|
|
mov a, r11
|
|
rorc a, 1
|
|
mov r11, a
|
|
mov a, r10
|
|
rorc a, 1
|
|
mov r10, a
|
|
mov a, r9
|
|
rorc a, 1
|
|
mov r9, a
|
|
mov a, r8
|
|
rorc a, 1
|
|
mov r8, a
|
|
|
|
incw bc
|
|
br $1b
|
|
1:
|
|
;; the previous loop leaves r15.r13 zero
|
|
mov a, r12
|
|
cmp0 a
|
|
bnz $1f
|
|
;; shift left, dec exponent
|
|
movw ax, r8
|
|
shlw ax, 1
|
|
movw r8, ax
|
|
movw ax, r10
|
|
rolwc ax, 1
|
|
movw r10, ax
|
|
movw ax, r12
|
|
rolwc ax, 1
|
|
movw r12, ax
|
|
;; don't need to do r14
|
|
decw bc
|
|
br $1b
|
|
1:
|
|
;; at this point, FRAC is in R8..R11 and EXP is in BC
|
|
movw ax, bc
|
|
movw A_EXP, ax
|
|
|
|
mov a, r9
|
|
mov A_FRAC_L, a
|
|
mov a, r10
|
|
mov A_FRAC_LH, a
|
|
mov a, r11
|
|
mov A_FRAC_H, a
|
|
mov a, r12
|
|
mov A_FRAC_HH, a
|
|
|
|
mov a, A_SIGN
|
|
xor a, B_SIGN
|
|
mov A_SIGN, a
|
|
|
|
call $!__rl78_int_pack_a_r8
|
|
|
|
addw sp, #16
|
|
ret
|
|
|
|
END_FUNC ___divsf3
|